A lead-bismuth fast reactor fuel assembly particle migration deposition test system and a test method thereof

Abstract

A lead-bismuth fast reactor fuel assembly particle migration deposition test system and a test method thereof, the system comprising a lead-bismuth circulating loop, an oxygen concentration control module, a data acquisition device, a detachable test section module, a feeding device and a particle filtering device; the lead-bismuth circulating loop comprises a lead storage tank, an electromagnetic pump, a preheating section, the detachable test section module and a heat exchanger; the detachable test section module comprises a test section outer tube, inlet and outlet detachable connection structures and a test inner core arranged inside the test section outer tube, the test inner core can be detached and replaced to form a straight pipe section flow channel or simulate a fuel rod bundle gap flow channel; preset cutting position marks and section number marks are arranged outside the test section outer tube; the feeding device is used for feeding particles into the test section outer tube, and the particle filtering device is used for capturing non-deposited particles; the application also provides a test method, after the test is completed, lead-bismuth is recovered and inert gas is blown, the test section outer tube and the test inner core are cut according to the preset cutting position marks and the section number marks, and electron microscope characterization analysis is performed on the samples.

Description

Technical Field

[0001] This invention belongs to the technical field of experimental research on liquid lead-bismuth circuits and fuel assembly deposition mechanisms, specifically relating to a test system and method for particle migration and deposition in lead-bismuth fast reactor fuel assemblies. Background Technology

[0002] Liquid lead-bismuth, as a coolant, possesses characteristics such as a high boiling point and good thermal conductivity, making it a promising candidate for application in fast reactor systems. In a liquid lead-bismuth environment, structural materials may undergo dissolution, oxidation, and corrosion product flaking under high-temperature flow, resulting in a certain amount of particulate impurities within the liquid lead-bismuth. Furthermore, to study the migration and deposition patterns of particles within the fuel assembly flow channels, it is necessary to introduce representative particles into the liquid lead-bismuth under controlled conditions.

[0003] Fuel assembly channels typically possess complex structures such as wire rod bundles, positioning grids, and bypass channels. Particles within these structures are influenced by factors such as inertia, gravity, fluid shear, and local eddies, resulting in migration and deposition characteristics that differ from those in straight pipe channels. To obtain comparable deposition data, it is necessary to achieve switchable simulations of straight pipe sections and rod bundle gap channels within the same experimental system, and to be able to perform high-resolution characterization of the deposition layer after the experiment.

[0004] In existing testing systems, test sections often adopt a fixed structure or are welded to the loop, making it inconvenient to disassemble them as a whole after the test. At the same time, the internal flow channel structure of the test section is complicated to replace, making it difficult to conduct comparative studies of various rod bundle / bypass structures under the same external tube conditions. In addition, if there is a lack of traceable cutting marks and section numbers, the cutting and numbering of the samples after the test can easily lead to differences, thereby reducing the comparability of deposition results of different structural sections.

[0005] Therefore, it is necessary to provide a detachable test section module, which allows the outer tube of the test section to be disassembled after lead and bismuth recovery and cut and sampled according to the section number. The switchable simulation of the gap structure between the straight tube section and the fuel rod bundle can be achieved through the replaceable test inner core, so as to meet the needs of particle migration and deposition law research and electron microscopy characterization. Summary of the Invention

[0006] The purpose of this invention is to address the problems of inconvenient disassembly, segmentation, structural switching, and sample traceability in existing deposition test sections by providing a lead-bismuth fast reactor fuel assembly particle migration deposition test system and its test method. This invention achieves rapid disassembly and replacement of the test core 404 and post-test segmentation sampling according to segment numbers by setting up a test core 404, end positioning components 405, guide components 406, and preset segmentation position markers 407 and segment number markers 408 in the detachable test section module 4. This allows for post-test segmentation sampling using electron microscopy to conduct deposition characterization analysis.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A lead-bismuth fast reactor fuel assembly particle migration and deposition test system includes a lead-bismuth circulation loop, an oxygen concentration control module 6, a data acquisition device 7, a detachable test section module 4, a feeding device 8, and a particle filtration device 9. The lead-bismuth circulation loop includes a lead storage tank 1, an electromagnetic pump 2, a preheating section 3, a detachable test section module 4, and a heat exchanger 5 connected sequentially by pipelines, forming a closed lead-bismuth circulation path. The detachable test section module 4 includes a test section outer tube 401, an inlet detachable connection structure 402, an outlet detachable connection structure 403, and a test inner core 404 disposed inside the test section outer tube 401. The test section outer tube 401 is provided with preset cutting position marks and sections along the axial direction. The test core 404 is detachable and replaceable, used to form a straight pipe section flow channel or a simulated fuel rod bundle gap flow channel, and the test core 404 is equipped with an end positioning component 405 and a guide component 406; the feeding device 8 is located above the test section outer pipe 401 and is connected to the test section outer pipe 401, used to add particles into the test section outer pipe 401 after the lead-bismuth circulation loop is stable; the particle filter device 9 is located in the lead-bismuth circulation loop, used to capture undeposited particles to reduce the risk of particles entering the electromagnetic pump 2; the oxygen concentration control module 6 is used to adjust and maintain the oxygen potential in the lead-bismuth circulation loop, and the data acquisition device 7 is used to collect and record temperature, pressure, flow rate and oxygen concentration parameters.

[0008] The outer pipe 401 of the test section is a pipe with an inner diameter of 38mm and a thickness of 3mm. The material is 316L or 321 stainless steel, which can withstand high temperature and meet the requirements of liquid lead bismuth flow. The axial reserved length is not less than 1.5m in order to obtain the complete axial distribution of the deposition. The design operating temperature is not lower than 450℃ and the design pressure is not lower than 1.0MPa.

[0009] The test section outer tube 401 is arranged horizontally, and both ends of the test section outer tube 401 are detachably connected to the lead-bismuth circulation loop through the inlet detachable connection structure 402 and the outlet detachable connection structure 403, respectively, so as to facilitate the disassembly and cutting of the test section outer tube 401 after the lead-bismuth is recovered.

[0010] The test core 404 includes a straight pipe section core 4041 and a simulated fuel rod bundle gap core; the simulated fuel rod bundle gap core includes one or more of the following: single rod core 4042, three rod core 4043, positioning grid 4044, wire rod bundle core 4045, and bypass arrangement core 4046. When the test core 404 is a wire-wound rod bundle core 4045, its geometric parameters meet the following requirements: rod outer diameter 8.2 mm, rod spacing 10.49 mm, pitch ratio 1.279, wire winding pitch 328 mm, wire winding diameter 2.2 mm, total test section length 1.5 m, and wire winding cover shaft length 1 m. This can effectively simulate the high-temperature narrow-slit spiral flow channel induced by wire winding in lead-bismuth reactor cores.

[0011] The particle filtration device 9 includes one of two options: a detachable strong magnetic filter 901 or a screen filter. The detachable strong magnetic filter 901 includes a filter housing 9011 and a magnetic field assembly 9012. The magnetic field assembly 9012 is detachably installed on the outside or inside of the filter housing 9011, so that when lead bismuth carrying ferromagnetic particles flows through the filter housing 9011, the particles are adsorbed and trapped under the action of the magnetic field. The filter screen, as one of the filtration schemes of the particle filtration device 9, is used to purify impurity particles in liquid lead bismuth.

[0012] The inlet detachable connection structure 402 and the outlet detachable connection structure 403 are connected by flanges or quick-release clamps, and metal gaskets or high-temperature resistant sealing gaskets are provided at the connection surfaces to facilitate disassembly and replacement and ensure sealing performance under high-temperature conditions.

[0013] The end positioning component 405 is an end plate, positioning ring, or support base. The end positioning component 405 is provided with positioning holes or positioning grooves for installing the test inner core 404, which are used to limit the axial position of the test inner core 404 and provide end support. The guide component 406 is a guide sleeve, guide key, or limiting block. The guide component 406 cooperates with the inner wall of the test section outer tube 401 to limit the radial offset and rotation of the test inner core 404.

[0014] The preset cutting position markings include engraved lines, grooves, dot marks, or combinations thereof set along the axial direction of the outer tube 401 of the test section, used to indicate the start and end positions of different structural sections, so as to facilitate cutting and sampling by section after the test; An insulation layer 410 and / or a heat tracing device 411 are provided on the outside of the outer pipe 401 of the test section. The insulation layer 410 is used to reduce heat loss, and the heat tracing device 411 is used to heat or keep the outer pipe 401 of the test section warm.

[0015] The detachable test section module 4 also includes a support member 409, which is located below the test section outer tube 401 and is used to support and position the test section outer tube 401.

[0016] The test method corresponding to the test system involves selecting either a straight pipe section core 4041 or a simulated fuel rod bundle gap core as the test core 404 before the test begins and installing it into the outer tube 401 of the test section, thus completing the assembly and sealing of the detachable test section module 4. The lead-bismuth temperature is raised to the target operating range via the preheating section 3. The oxygen potential in the lead-bismuth circulation loop is adjusted and stabilized via the oxygen concentration control module 6. After the lead-bismuth circulation loop is established and stabilized, particles are added into the outer tube 401 of the test section via the feeding device 8 and maintained for a preset test duration under target flow and temperature conditions to complete the deposition process. During the deposition experiment, the particle filter 9 collects undeposited particles, and the data acquisition device 7 records the temperature, pressure, flow rate, and oxygen concentration parameters during the stabilization and feeding stages. After the experiment, lead and bismuth are recovered, and the lead and bismuth circulation loop is purged with inert gas to remove residual lead and bismuth and particles. The detachable test section module 4 is disassembled, and the outer tube 401 and / or inner core 404 of the test section are cut and sampled according to the preset cutting position markings and section number markings. The cut samples are observed under an electron microscope, and the deposition characteristics of the straight tube section and the rod bundle gap section are compared and analyzed.

[0017] The section numbering identifier includes the section number set on the outer surface of the outer tube 401 of the test section. The section number is 01, 02, 03, 04, 05. Among them, number 01 corresponds to the inlet development section, number 02 corresponds to the straight pipe section main test section, number 03 corresponds to the rod bundle gap section, number 04 corresponds to the bypass section, and number 05 corresponds to the outlet stabilization section. The electron microscopy observations included characterization of sedimentary morphology, sedimentary coverage, sedimentary thickness and elemental distribution, and recording of the differences in sedimentary distribution between straight pipe sections and rod bundle interstitial sections; The slicing and sampling includes axially slicing the outer tube 401 of the test section and / or radially slicing a local area to obtain cross-sectional and surface samples for electron microscopy observation.

[0018] Compared with the prior art, the present invention has the following advantages: 1. The detachable test section module 4 achieves a detachable sealed connection through the inlet detachable connection structure 402 and the outlet detachable connection structure 403, which facilitates the overall disassembly and segmentation for sampling after lead and bismuth recovery, meeting the needs of electron microscopy characterization. 2. The test inner core 404 is detachable and replaceable, and the consistency of repeated assembly can be achieved through the end positioning part 405 and the guide part 406. Under the same test section outer tube 401 conditions, a comparative study of the straight pipe section inner core 4041 and various rod bundle / bypass inner core schemes can be carried out. 3. Pre-set cutting position markers and segment number markers clearly indicate the sample segment numbers 01, 02, 03, 04, and 05 and their corresponding positions, improving the repeatability of sample numbering, traceability, and segment comparison; 4. The feeding device 8 can controllably introduce particles under stable lead-bismuth circulation conditions, and the particle filtration device 9 can capture and recover particles, and reduce the risk of particles entering the electromagnetic pump 2. 5. The experimental method matches the disassembly, cutting and electron microscopy characterization process with the experimental section structure design, which can realize the structured acquisition and comparative analysis of the deposited samples. Attached Figure Description

[0019] Figure 1 This is a system diagram of the test system of the present invention.

[0020] Figure 2 This is a schematic diagram of the detachable test section module structure.

[0021] Figure 3 This is a schematic diagram of the experimental core structure.

[0022] Figure 4 This is a schematic diagram of a particle filtration device. Detailed Implementation

[0023] The invention will now be further described with reference to the accompanying drawings: like Figure 1 As shown, the lead-bismuth fast reactor fuel assembly particle migration and deposition test system of the present invention includes a lead-bismuth circulation loop, an oxygen concentration control module 6, a data acquisition device 7, a detachable test section module 4, a feeding device 8, and a particle filtration device 9. The lead-bismuth circulation loop includes a lead storage tank 1, an electromagnetic pump 2, a preheating section 3, a detachable test section module 4, and a heat exchanger 5, which are connected in sequence by pipelines. The lead storage tank 1 is used to store lead-bismuth alloy and provide buffer volume, the electromagnetic pump 2 is used to provide circulation power, the preheating section 3 is used to heat or keep the lead-bismuth alloy at a certain temperature, the heat exchanger 5 is used to remove or regulate the heat in the loop, the oxygen concentration control module 6 is used to regulate and maintain the oxygen potential in the lead-bismuth circulation loop, and the data acquisition device 7 is used to collect and record operating parameters.

[0024] like Figure 2 As shown, the detachable test section module 4 includes a test section outer tube 401, an inlet detachable connection structure 402, an outlet detachable connection structure 403, a test inner core 404, an end positioning component 405, a guide component 406, a preset cutting position marker, and a section number marker. In one embodiment, the test section outer tube 401 is arranged horizontally and supported and positioned by a support component 409; the support component 409 can be a support base, bracket, or clamping structure, and is used to limit the sinking or vibration displacement of the test section outer tube 401 during operation.

[0025] The outer pipe 401 of the test section is equipped with a detachable inlet connection structure 402 and a detachable outlet connection structure 403 at both ends. The detachable inlet connection structure 402 and the detachable outlet connection structure 403 can be connected by flanges or quick-release clamps. Metal gaskets or high-temperature resistant sealing gaskets are installed at the connection surfaces to achieve detachable sealing. The detachable inlet connection structure 402 and the detachable outlet connection structure 403 allow the outer pipe 401 of the test section to be completely disassembled after lead and bismuth recovery, facilitating subsequent cutting and sampling.

[0026] In a preferred embodiment, an insulation layer 410 and / or a heat tracing device 411 are provided on the outside of the test section outer tube 401. The insulation layer 410 is used to reduce heat loss along the test section outer tube 401, and the heat tracing device 411 is used to heat or insulate the test section outer tube 401 so that the test section outer tube 401 matches the thermal boundary conditions of the preheating section 3 and the heat exchanger 5.

[0027] like Figure 3 As shown, the test inner core 404 can be replaced with a straight pipe section inner core 4041 or a simulated fuel rod bundle gap inner core. The simulated fuel rod bundle gap inner core can be a single-rod inner core 4042, a three-rod inner core 4043, a positioning grid 4044, a wound-rod bundle inner core 4045, or a bypass arrangement inner core 4046. By replacing the test inner core 404, different target flow channels can be constructed under the same test section outer pipe 401 conditions.

[0028] The end positioning member 405 is used to define the axial position of the test core 404 and bear the end load generated by the test core 404 under the action of lead-bismuth flow. In one embodiment, the end positioning member 405 is an end plate structure, and the end plate is provided with positioning holes or positioning grooves for mounting fuel rod simulators; in another embodiment, the end positioning member 405 is a positioning ring or support structure, and the positioning ring or support is used to limit the engagement with the inner wall or connecting end of the test section outer tube 401.

[0029] The guide component 406 is used to ensure the coaxiality and attitude stability of the test core 404 within the outer tube 401 of the test section. The guide component 406 can be in the form of a guide sleeve, guide key, or limiting block. The guide component 406 forms a clearance fit or sliding fit with the inner wall of the outer tube 401 of the test section to limit the radial displacement of the test core 404 and suppress the rotation of the test core 404. When the test core 404 is a wound rod bundle core 4045 or a bypass arrangement core 4046, the guide component 406 can achieve orientation consistency, which facilitates the comparative analysis of section samples.

[0030] In one implementation, section number 01 corresponds to the inlet development section, section number 02 corresponds to the straight pipe main test section, section number 03 corresponds to the rod bundle gap section, section number 04 corresponds to the bypass section, and section number 05 corresponds to the outlet stabilization section. By coordinating the preset cutting position markers with the section number markers, after the test, the outer pipe 401 and the inner core 404 of the test section can be uniformly cut and sampled according to the section number, and samples under different test inner core 404 schemes can have a traceable spatial correspondence.

[0031] like Figure 1 As shown, the feeding device 8 is positioned above and connected to the outer pipe 401 of the test section. In one embodiment, the feeding device 8 includes a feeding bin, a feeding valve, and a feeding pipe. The feeding bin is used to store the particles to be added, the feeding valve is used to control the timing and amount of particle addition, and the feeding pipe is used to guide the particles into the outer pipe 401 of the test section.

[0032] The feeding device 8 may be equipped with an inert gas interface, which is used to replace or purge the feeding bin and feeding pipe. The feeding device 8 may also be equipped with a check valve structure, which is used to restrict the backflow of lead and bismuth along the feeding pipe. Through the above structures, the feeding device 8 can achieve controllability of the introduction and addition process of particles under closed conditions.

[0033] like Figure 4 As shown, the particle filter 9 is installed in the lead-bismuth circulation loop to capture undeposited particles and achieve particle recovery. In one embodiment, the particle filter 9 is arranged in the loop pipe section on the inlet or outlet side of the electromagnetic pump 2 to facilitate particle capture during loop operation.

[0034] When the particle filtration device 9 adopts a detachable strong magnetic filter 901, the detachable strong magnetic filter 901 includes a filter housing 9011 and a magnetic field assembly 9012. A flow channel for lead-bismuth fluid is formed inside the filter housing 9011. The magnetic field assembly 9012 is detachably installed on the outside or inside of the filter housing 9011, so that when lead-bismuth carrying ferromagnetic particles flows through the filter housing 9011, the particles are adsorbed and retained under the action of the magnetic field. After the magnetic field assembly 9012 is disassembled, the adsorbed particles on the inner wall or bottom of the filter housing 9011 can be collected.

[0035] When the particle filtration device 9 adopts the screen filter scheme, the screen filter is used to purify the impurity particles in liquid lead bismuth. The screen pore size, screen material and installation method of the screen filter can be selected according to the test requirements.

[0036] The test method of the test system of the present invention is as follows: Before the test begins, the test inner core 404 is selected as the straight pipe section inner core 4041 or the simulated fuel rod bundle gap inner core and installed in the test section outer tube 401. The positioning and orientation verification of the test inner core 404 are completed by the end positioning component 405 and the guide component 406. The assembly and sealing connection of the detachable test section module 4 is completed by the inlet detachable connection structure 402 and the outlet detachable connection structure 403.

[0037] Subsequently, the lead-bismuth circulation loop is heated to the target operating temperature range via preheating section 3. The oxygen potential within the loop is regulated and stabilized using oxygen concentration control module 6, while data acquisition device 7 records the temperature, pressure, flow rate, and oxygen concentration during the stabilization phase. After the lead-bismuth circulation loop stabilizes, particles are added to the outer pipe 401 of the test section via feeding device 8 controlled by feeding valve, and maintained at the target flow rate and temperature for a certain test duration to complete the deposition process.

[0038] During the experiment, the particle filtration device 9 collects undeposited particles. When the particle filtration device 9 is a detachable strong magnetic filter 901, ferromagnetic particles can be adsorbed and retained by the magnetic field component 9012; when the particle filtration device 9 is a screen filter 902, particles can be intercepted by the screen. The data acquisition device 7 continuously or intermittently records the operating parameters of the feeding stage and the filtration stage.

[0039] After the test, lead and bismuth are recovered, and the lead and bismuth circulation loop and the detachable test section module 4 are purged with inert gas to remove residual lead and bismuth and particles. Subsequently, the detachable test section module 4 is disassembled, and the outer tube 401 of the test section is cooled and its outer surface is cleaned if necessary. After disassembly, the test core 404 can be removed entirely from the outer tube 401 of the test section, or the test core 404 and the outer tube 401 can be kept in the assembled state for overall cutting and sampling.

[0040] During the slicing and sampling process, the outer tube 401 and / or the inner core 404 of the test section are sliced ​​according to the preset slicing position markers and section number markers to obtain sample sections numbered 01, 02, 03, 04, and 05. For each sample section, samples can be obtained from the inner wall surface of the outer tube, the surface of the inner core 404, and the radial cross-section. The samples are then observed using electron microscopy, which includes characterization of the sedimentary morphology, sedimentary coverage, sedimentary thickness, and elemental distribution. A comparative analysis of the depositional characteristics of the main test section (straight tube section, number 02) and the interstitial section (bar bundle section, number 03) is also conducted.

[0041] Example 1: Implementation of the deposition test of the inner core 4045 of the wire-wound rod bundle. The test inner core 404 was selected as the inner core 4045 of the wire-wound rod bundle. The end of the rod bundle was positioned by the end positioning component 405, and the orientation of the inner core 4045 of the wire-wound rod bundle was aligned by the guide component 406. After the test, the detachable test section module 4 was disassembled, and the section was divided into sections according to the section numbering 03. The surface of the rod bundle and the inner wall of the outer tube were characterized by electron microscopy.

[0042] Example 2: Sampling Implementation Method for Local Enrichment Area of ​​Positioning Grid 4044. The test core 404 is selected as the positioning grid 4044. The positioning grid 4044 is arranged at a predetermined position in the axial direction of the test core 404, and this position is set as the preset cutting position mark of section number 03. After the test, radial cross-section cutting sampling is performed near section number 03 to obtain the sediment cross-section sample near the positioning grid 4044, and the sample is observed by electron microscopy.

[0043] Example 3: Comparative Sampling Implementation of Bypass Arrangement Core 4046. The test core 404 was selected as a bypass arrangement core 4046, with the bypass pipe and main channel arranged in parallel and correspondingly assigned section number 04. After the test, samples were taken from the main channel area (section number 03) and the bypass section area (section number 04) respectively. The deposition on the inner wall of the bypass pipe and the main channel deposition were compared and analyzed to obtain comparative data on the influence of the bypass structure on particle migration and deposition.

Claims

1. A test system for particle migration and deposition of lead-bismuth fast reactor fuel assemblies, characterized in that: The system includes a lead-bismuth circulation loop, an oxygen concentration control module (6), a data acquisition device (7), a detachable test section module (4), a feeding device (8), and a particle filtration device (9). The lead-bismuth circulation loop includes a lead storage tank (1), an electromagnetic pump (2), a preheating section (3), a detachable test section module (4), and a heat exchanger (5) connected in sequence by pipes, forming a closed lead-bismuth circulation path. The detachable test section module (4) includes a test section outer tube (401), an inlet detachable connection structure (402), an outlet detachable connection structure (403), and a test inner core (404) set inside the test section outer tube (401). The test section outer tube (401) is provided with a preset cutting position mark and a section number mark along the axial direction. The test core (404) is detachable and replaceable, used to form a straight pipe section flow channel or a simulated fuel rod bundle gap flow channel, and the test core (404) is provided with end positioning parts (405) and guide parts (406); the feeding device (8) is set above the test section outer pipe (401) and connected to the test section outer pipe (401), used to add particles into the test section outer pipe (401) after the lead-bismuth circulation loop is stable; the particle filter device (9) is set in the lead-bismuth circulation loop, used to capture undeposited particles to reduce the risk of particles entering the electromagnetic pump (2); the oxygen concentration control module (6) is used to adjust and maintain the oxygen potential in the lead-bismuth circulation loop, and the data acquisition device (7) is used to collect and record temperature, pressure, flow rate and oxygen concentration parameters.

2. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The outer pipe (401) of the test section is a pipe with an inner diameter of 38mm and a thickness of 3mm. The material is 316L or 321 stainless steel. The design working temperature is not lower than 450℃, the design pressure is not lower than 1.0MPa, and the axial reserved length is not less than 1.5m. The test section outer tube (401) is arranged horizontally, and both ends of the test section outer tube (401) are detachably connected to the lead-bismuth circulation loop (10) through the inlet detachable connection structure (402) and the outlet detachable connection structure (403) respectively, so as to facilitate the disassembly and cutting of the test section outer tube (401) after the lead-bismuth is recovered.

3. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The test core (404) includes a straight pipe section core (4041) and a simulated fuel rod bundle gap core; the simulated fuel rod bundle gap core includes one or more of the following: a single rod core (4042), a three-rod core (4043), a positioning grid (4044), a wire-wound rod bundle core (4045), and a bypass arrangement core (4046); When the test core (404) is the core (4045) of the wire-wound rod bundle, its geometric parameters satisfy: outer diameter of the rod 8.2 mm, spacing between rods 10.49 mm, pitch ratio 1.279, wire-wound pitch 328 mm, wire-wound diameter 2.2 mm, total length of the test section 1.5 m, and length of the wire-wound covering shaft 1 m.

4. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The particle filtration device (9) includes one of two options: a detachable strong magnetic filter (901) or a screen filter; The detachable strong magnetic filter (901) includes a filter housing (9011) and a magnetic field assembly (9012). The magnetic field assembly (9012) can be detachably installed on the outside or inside of the filter housing (9011) so that when lead bismuth carrying ferromagnetic particles flows through the filter housing (9011), the particles are adsorbed and trapped under the action of the magnetic field. The filter screen is one of the filtration schemes of the particle filtration device (9) and is used to purify impurity particles in liquid lead bismuth.

5. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The inlet detachable connection structure (402) and the outlet detachable connection structure (403) are flange connections or quick-release clamp connections, and metal gaskets or high-temperature resistant sealing gaskets are provided at the connection surfaces.

6. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The end positioning component (405) is an end plate, positioning ring, or support base. The end positioning component (405) is provided with positioning holes or positioning grooves for installing the test inner core (404), which are used to limit the axial position of the test inner core (404) and provide end support. The guide component (406) is a guide sleeve, guide key, or limiting block. The guide component (406) cooperates with the inner wall of the test section outer tube (401) to limit the radial offset and rotation of the test inner core (404).

7. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The preset cutting position markings include engraved lines, grooves, dot marks, or combinations thereof set along the axial direction of the outer tube (401) of the test section, used to indicate the start and end positions of different structural sections; The outer side of the test section outer pipe (401) is provided with a heat insulation layer (410) and / or a heat tracing device (411). The heat insulation layer (410) is used to reduce heat loss, and the heat tracing device (411) is used to heat or insulate the test section outer pipe (401).

8. The lead-bismuth fast reactor fuel assembly particle migration and deposition test system according to claim 1, characterized in that: The detachable test section module (4) also includes a support (409), which is located below the test section outer tube (401) and is used to support and position the test section outer tube (401).

9. The test method corresponding to the test system according to any one of claims 1 to 8, characterized in that: Before the test begins, the test core (404) is selected as either a straight pipe section core (4041) or a simulated fuel rod bundle gap core and installed into the test section outer tube (401) to complete the assembly and sealing of the detachable test section module (4); the lead-bismuth temperature is raised to the target operating range through the preheating section (3), and the oxygen potential in the lead-bismuth circulation loop is adjusted and stabilized through the oxygen concentration control module (6). After the lead-bismuth circulation loop is established and stabilized, particles are added into the test section outer tube (401) through the feeding device (8) and the preset test time is maintained under the target flow rate and temperature conditions to complete the deposition process. During the experiment, the particle filtration device (9) collected the undeposited particles, and the temperature, pressure, flow rate and oxygen concentration parameters of the stabilization stage and the feeding stage were recorded by the data acquisition device (7). After the experiment, lead and bismuth were recovered, and the lead and bismuth circulation loop was purged with inert gas to remove residual lead and bismuth and particles. The detachable test section module (4) was disassembled, and the test section outer tube (401) and / or test inner core (404) were cut and sampled according to the preset cutting position mark and section number mark. The cut samples were observed by electron microscopy, and the deposition characteristics of the straight tube section and the rod bundle gap section were compared and analyzed.

10. The test method according to claim 9, characterized in that: The section numbering identifier includes the section number set on the outer surface of the test section outer pipe (401), and the section number is 01, 02, 03, 04, 05; wherein number 01 corresponds to the inlet development section, number 02 corresponds to the straight pipe section main test section, number 03 corresponds to the rod bundle gap section, number 04 corresponds to the bypass section, and number 05 corresponds to the outlet stabilization section. The electron microscopy observations included characterization of sedimentary morphology, sedimentary coverage, sedimentary thickness and elemental distribution, and recording of the differences in sedimentary distribution between straight pipe sections and rod bundle interstitial sections; The sectional sampling includes axially segmenting the outer tube (401) of the test section and / or radially segmenting a local area to obtain cross-sectional and surface samples for electron microscopy observation.

Images