Testing device for coating cladding

Abstract

The invention provides a coating cladding testing device which comprises a simulation cladding located in a high-temperature and high-pressure water environment, the outer wall of the simulation cladding is coated with a coating, a closed cavity is defined by the simulation cladding, and the internal pressure of the cavity is adjustable; the heating rod is arranged in the cavity of the simulation cladding, a plurality of annular ridges are arranged on the heating rod, the annular ridges are arranged in the axial direction of the heating rod at intervals, and the annular ridges annularly protrude in the radial direction of the heating rod; wherein the ring surface, located on the outermost side in the radial direction, of the ring ridge makes contact with the inner wall of the simulation cladding, a through hole is formed in the ring ridge, and the through hole penetrates through the two opposite side faces, in the axial direction, of the ring ridge. And testing the performance of the coating cladding in a high-temperature and high-pressure water environment and internal stress change coupling scene.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pressurized water reactors, and in particular to a testing device for coated cladding. BACKGROUND

[0002] With the development of coated cladding, the long-term service performance of coated cladding, especially the failure mechanism under the coupling effect of corrosion-mechanics existing in actual reactors, still needs in-depth research and reliable evaluation. Current coated cladding material testing focuses more on separate performance evaluation, for example, basic mechanical properties (such as strength, hardness, toughness) of the coating material are tested using a universal mechanical testing machine, ring pressure experiments, hoop tensile tests, internal pressure burst tests, internal pressure creep tests, etc. These tests can be performed at room temperature or at high temperature, but cannot be coupled with dirt deposition for testing. For example, corrosion performance (such as uniform corrosion, pimple corrosion, under-deposit corrosion) testing is performed, and currently high-pressure autoclaves are commonly used for coupon corrosion experiments, which cannot simulate the internal pressure creep atmosphere.

[0003] Most existing experimental devices can only simulate a single working condition, such as pure high-temperature water corrosion experiments, high-temperature mechanical loading experiments, or boiling heat transfer experiments, and cannot simultaneously reproduce the multi-field coupling conditions faced by the cladding in actual operation. This leads to insufficient understanding of the failure mechanism of coated cladding under complex service environments, and a lack of relevant experimental verification methods, thereby restricting the research and engineering application of new coated cladding materials.

[0004] Overall, there is currently a serious lack of testing devices that can completely simulate the failure process of coated cladding, and existing testing equipment cannot reproduce the entire process of coated cladding coating failure for research. It is difficult to simulate the periodic mechanical load of the PCMI (Particle-Cladding Mechanical Interaction) mechanical effect on the sample to induce bamboo deformation and coating cracking in the high-temperature and high-pressure water chemical environment of the pressurized water reactor primary loop. It is difficult to study the changes in nucleate boiling behavior (such as bubble nucleation frequency, departure diameter, etc.) and their interaction with CRUD (Corrosion Product Deposition on the Surface of the Pressurized Water Reactor Fuel Element) on the surface of coated cladding samples with existing cracks or defects. At present, there is still a significant lack of means for integrity evaluation of coated cladding under the condition of "corrosion-mechanical coupling-nucleate boiling environment", and there is a lack of means to study the local chemical microenvironment inside the coating cracks and under the scale and its influence on the local dissolution of the coating and the corrosion process of the substrate. SUMMARY

[0005] The present application at least aims to provide a testing device for coated cladding, which can simulate the stress state of the fuel rod in a high-temperature and high-pressure water environment to test the performance of the coated cladding in a coupling scenario of high-temperature and high-pressure water environment and internal stress variation.

[0006] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0007] One of the embodiments of the present application provides a test device for coating cladding, the test device comprising:

[0008] A simulation cladding, the simulation cladding is located in a high-temperature and high-pressure water environment, an outer wall of the simulation cladding is coated with a coating, and the simulation cladding defines a sealed cavity, an internal pressure of the cavity is adjustable;

[0009] A heating rod, the heating rod is arranged in the cavity of the simulation cladding, a plurality of annular ridges are arranged on the heating rod, the plurality of annular ridges are arranged at intervals in an axial direction of the heating rod, and the annular ridges are annularly protruded in a radial direction of the heating rod; wherein,

[0010] An annular surface of the annular ridges located at an outermost side in the radial direction is in contact with an inner wall of the simulation cladding, and a through hole is arranged on the annular ridges, the through hole penetrates through opposite sides of the annular ridges in the axial direction, so as to keep the internal pressure of the cavity uniform.

[0011] In some embodiments, the simulation cladding is in a tubular structure and is coaxially arranged with the heating rod.

[0012] In some embodiments, the axial spacing between adjacent annular ridges on the heating rod is close or consistent.

[0013] In some embodiments, the through hole also penetrates through the annular surface of the annular ridges located at the outermost side in the radial direction.

[0014] In some embodiments, the test device comprises a pressure supply system for inflating or deflating the cavity of the simulation cladding, so as to simulate the internal pressure creep state in the heating process of the fuel rod.

[0015] In some embodiments, an air inlet and an air outlet are arranged on the simulation cladding, and the air inlet and the air outlet are both in communication with the cavity;

[0016] The pressure supply system comprises a gas source and a booster pump, the gas source is connected with the air inlet through the booster pump to realize inflation and pressure increase, and a gas back pressure valve is arranged at the air outlet to realize stable pressure exhaust.

[0017] In some embodiments, the test device comprises a high-temperature and high-pressure water loop system for providing a high-temperature and high-pressure water environment simulating a primary loop of a pressurized water reactor.

[0018] In some embodiments, the high-temperature and high-pressure water loop system comprises:

[0019] a material tank for storing an aqueous solution simulating a water chemistry environment of a primary circuit of a pressurized water reactor;

[0020] a high-pressure pump for pressurizing the aqueous solution, an inlet of the high-pressure pump being connected to an outlet of the material tank;

[0021] a heating assembly for heating the pressurized aqueous solution, an inlet of the heating assembly being connected to an outlet of the high-pressure pump;

[0022] an autoclave for containing the pressurized and heated aqueous solution and isolating the aqueous solution from the outside, providing a high-temperature and high-pressure water environment, an inlet of the autoclave being connected to an outlet of the heating assembly, and a cladding is placed in the aqueous solution in the autoclave.

[0023] In some embodiments, the heating assembly comprises:

[0024] a preheating device for preheating the pressurized aqueous solution, an inlet of the preheating device being connected to an outlet of the high-pressure pump;

[0025] a heat exchange device for heating the pressurized aqueous solution by using heat of an effluent of the autoclave, a cold end inlet of the heat exchange device being connected to an outlet of the preheating device, a cold end outlet of the heat exchange device being connected to an inlet of the autoclave, and an outlet of the autoclave being connected to a hot end inlet of the heat exchange device.

[0026] In some embodiments, the high-temperature and high-pressure water loop system further comprises a cooling device and a water treatment device, the cooling device being used for cooling the effluent, an inlet of the cooling device being connected to a hot end outlet of the heat exchange device, and an outlet of the cooling device being communicated with an inlet of the material tank through the water treatment device, the water treatment device being used for treating the cooled effluent.

[0027] In some embodiments, a liquid back pressure valve is arranged on a flow path between the hot end outlet of the heat exchange device and the inlet of the material tank, the liquid back pressure valve being used for maintaining pressure balance of the high-temperature and high-pressure water loop system.

[0028] In some embodiments, a temperature monitoring element is installed in the autoclave, and is used for monitoring temperature of the aqueous solution in the autoclave.

[0029] The test device for the coated cladding can comprehensively simulate cladding stress variation, subcooled nucleate boiling, corrosion product deposition and under-deposit chemical environment, and has great engineering application value and theoretical significance for revealing failure mechanism of the chromium coated cladding, evaluating service integrity and life of the coated cladding, and guiding research and development of new accident tolerant coated cladding materials. Specifically,

[0030] The ring ridge heating rod can simulate the shape of the deformed pellet, and the mechanical property environment of the cladding under the scenario of pellet contact is formed by adjusting the internal pressure of the cladding, so that the surface characteristics of the bamboo joint cladding are simulated quickly, and the coating is cracked to form a nucleation site for bubble nucleate boiling. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above features and advantages of the present application will be better understood through reading the detailed description of the embodiments of the present application in conjunction with the following drawings, in which: In the drawings, components are not necessarily drawn to scale, and components having similar related functions or features can have the same or similar reference labels. Among them:

[0032] Figure 1 is a schematic diagram of the failure process of the coated cladding;

[0033] Figure 2 is a structural schematic diagram of a test device for a coated cladding according to some embodiments;

[0034] Figure 3 is a structural schematic diagram of a simulated fuel rod according to some embodiments;

[0035] Figure 4 is a radial plane view of the ring ridge on the heating rod according to some embodiments. DETAILED DESCRIPTION

[0036] The present application will be described in detail below in conjunction with the drawings and specific embodiments. It should be noted that the aspects described below in conjunction with the drawings and specific embodiments are only exemplary and should not be understood as limiting the scope of protection of the present application.

[0037] It should be understood that "system" and "device" used herein are a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0038] It can be understood that the technical terms involved in the description of the present application, such as "inner", "outer" and the like, indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the embodiments, and does not indicate or imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as a limitation on the scope of protection of the invention.

[0039] It should be noted that the use of terms such as "first" and "second" to define features in this document is merely for the purpose of distinguishing the corresponding features. Unless otherwise stated, these terms have no special meaning and should not be construed as limiting the scope of protection of this invention. As shown in this specification and claims, terms such as "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural, unless the context clearly indicates otherwise. Generally, the term "comprising" only indicates the inclusion of explicitly identified elements, which do not constitute an exclusive list of devices and may also include other elements.

[0040] During the long-term operation of a pressurized water reactor (PWR), the cladding encases the fuel rods and fuel pellets. As fuel burnup increases, the fuel pellets deform to some extent due to factors such as sintering shrinkage, cracking swelling, and rearrangement. This deformation interacts with the inner wall of the cladding, generating a ratchet effect, such as... Figure 1 ( Figure 1 As shown in the schematic diagram of the coating failure process, periodic stress zones often form along the axial direction of the coating. Simultaneously, the internal pressure power of the coating changes instantaneously, causing internal pressure fluctuations and leading to creep. Under the combined effects of ratcheting and creep, the coating exhibits "bamboo-like" deformation, specifically annular protrusions on the coating surface. This "bamboo-like" deformation alters the local stress distribution of the coating to some extent, making the coating more prone to cracking and generating microcracks in stress concentration areas.

[0041] In the primary circuit of a pressurized water reactor, the fuel rod cladding must withstand not only the mechanical forces from the fuel pellets but also the corrosive effects of the high-temperature, high-pressure aqueous chemical environment. The cladding is situated in this high-temperature, high-pressure aqueous chemical environment, and its surface is typically in a state of subcooled boiling or localized nucleation boiling. For example... Figure 1 As shown, when microcracks develop in the coating on the cladding surface, these microcracks act as boiling initiation points, leading to intensified surface nucleation boiling. This increased nucleation boiling intensity not only alters local heat transfer characteristics but also accelerates the deposition of corrosion products and hydrochemical impurities on the cladding surface. As fouling on the cladding surface worsens, under-deposit corrosion occurs between the scale and the coating. Furthermore, over time, the corrosion at the film-substrate interface intensifies, often resulting in pitting or localized dissolution of the coating (e.g., chromium coatings).

[0042] Once the coating peels off, the exposed cladding substrate (such as a zirconium alloy substrate) is directly exposed to a high-temperature, high-pressure water environment, which not only accelerates its oxidation rate but may also lead to hydride formation and mechanical property degradation. Under long-term effects, the synergistic effect of external chemical corrosion and internal stress changes may eventually induce overall coating failure or even cladding damage, directly affecting the integrity of the core fuel and the safe operation of the reactor, with extremely serious consequences.

[0043] Therefore, it is necessary to test the performance change of the coated cladding under the synergistic effect of external chemical corrosion and internal stress change in advance. The embodiment of the present specification proposes a test device for coated cladding to realize the performance test of the coated cladding under the synergistic effect of external chemical corrosion and internal stress change, which can reproduce the whole process of crack initiation of the coated cladding, crack propagation, CRUD deposition, under-deposit corrosion and coating damage.

[0044] In some embodiments, the test device for coated cladding can be used to verify the whole process evolution ability of the chromium-coated zirconium alloy cladding tube from crack initiation to under-deposit corrosion penetration under the simulated typical start-stop cycle working condition of the pressurized water reactor, and to evaluate the effectiveness of the chromium-coated zirconium alloy cladding tube as an anti-accident fuel (ATF) fuel performance verification platform.

[0045] Figure 2 is a structural schematic diagram of a test device for coated cladding according to some embodiments; Figure 3 is a structural schematic diagram of a simulated cladding according to some embodiments.

[0046] As shown in Figure 2 , the test device includes a simulated fuel rod 6, a high-temperature high-pressure water loop system and a pressure supply system.

[0047] As shown in Figure 3 , the simulated fuel rod 6 includes a simulated cladding 18 and a heating rod 16.

[0048] The simulated cladding 18 is used to simulate the coated cladding in actual application. The outer wall of the simulated cladding 18 is coated with a coating. The simulated cladding 18 defines a closed cavity, the internal cavity of the simulated cladding 18 is isolated from the external environment, can withstand a certain degree of internal pressure, and the internal pressure can be adjusted. In some embodiments, the simulated cladding 18 adopts a tubular structure, the axial dimension of the simulated cladding 18 is greater than the radial dimension, and the wall thickness of the simulated cladding 18 is uniform everywhere. The axial and radial directions described in the present specification refer to Figure 3 , the axial direction is the vertical direction of the Figure 3 view. The axial direction is perpendicular to the radial plane where the radial direction is located, and the radial plane is the transverse cross section of the simulated cladding 18.

[0049] The heating rod 16 is arranged in the cavity of the simulated cladding 18, and the heating rod 16 heats the cavity of the simulated cladding 18 to simulate the heat release process of the fuel pellets inside the coated cladding. In some embodiments, as shown in Figure 3As shown, the heating rod 16 is powered by the external power supply line 14 to generate heat. In some embodiments, the heating rod 16 is sprayed with an insulating coating on the surface. The heating rod 16 has a bumpy structure, and a plurality of annular ridges 20 are arranged on the heating rod 16. The annular ridges 20 are arranged at intervals in the axial direction of the heating rod 16, and are annularly protruded in the radial direction of the heating rod 16. The outermost annular surface of the annular ridges 20 is in contact with the inner wall of the simulated cladding 18. The area between the annular ridges 20 on the heating rod 16 and the inner wall of the simulated cladding 18 has an air gap 17.

[0050] In some embodiments, when the simulated cladding 18 adopts a tubular structure, the simulated cladding 18 is coaxially arranged with the heating rod 16, so that the heating effect of the heating rod 16 on the cavity of the simulated cladding 18 is consistent or close everywhere. In some embodiments, a through hole 19 is arranged on the annular ridge 20, which serves as a gas flow channel in the simulated cladding 18. The through hole 19 penetrates through the opposite sides of the annular ridge 20 in the axial direction, so as to maintain the uniformity of the internal pressure of the cavity. In this embodiment, the axial spacing between adjacent annular ridges 20 on the heating rod 16 is close or consistent. In some embodiments, as shown, the through hole 19 also penetrates through the outermost annular surface of the annular ridge 20 in the radial direction, Figure 4 as shown, the through hole 19 also penetrates through the outermost annular surface of the annular ridge 20 in the radial direction, Figure 4 As shown, the radial plane at the annular ridge 20 on the heating rod 16 is shown.

[0051] By arranging a plurality of annular ridges 20 on the heating rod 16 in the axial direction, the annular ridges 20 are in contact with the inner wall of the simulated cladding 18. Under the action of the internal pressure in the simulated cladding 18, the area of the simulated cladding 18 corresponding to the annular ridges 20 is deformed in a convex shape, which induces stress concentration on the corresponding outer surface area of the simulated cladding 18. The area of the simulated cladding 18 corresponding to adjacent annular ridges 20 is deformed in a concave shape, which can simulate the "bumpy" deformation of the coating cladding, and further cause the coating on the corresponding outer surface of the simulated cladding 18 to crack, thereby realizing the mechanism simulation of coating crack initiation and propagation.

[0052] The pressure supply system inflates or deflates the cavity of the simulated cladding 18 to simulate the internal pressure creep state during the heating process of the fuel rod. The pressure supply system includes a gas source and a booster pump 11. In some embodiments, the gas source is a group of inert gas bottles 10 filled with chemically inert gas. The simulated cladding 18 is provided with an air inlet and an air outlet, both of which are in communication with the cavity thereof. The gas source is connected with the air inlet through the booster pump 11 to realize inflation and pressure increase. In some embodiments, a first sleeve 15 is arranged on the air inlet, and the booster pump 11 is sealingly connected with the air inlet through the first sleeve 15, so as to ensure the high-pressure air tightness of the cavity of the simulated cladding 18. A gas back pressure valve 12 is arranged at the air outlet to realize stable pressure relief. In some embodiments, a second sleeve 13 is arranged on the air outlet, and the air outlet is connected with the gas back pressure valve 12 through the second sleeve 13 to maintain the stability of gas flow.

[0053] In some embodiments, the pressure supply system controls the periodic application of internal pressure to the cavity of the simulation cladding 18, for example 0→12 MPa→0, simulating the internal pressure fluctuation caused by start-stop of the reactor, with a frequency of one cycle per 24 hours, and a total of 100 cycles. In some embodiments, the pressure supply system also has the function of monitoring the integrity of the simulation cladding 18.

[0054] After the gas is pressurized by the booster pump 11, it enters the inside of the simulation cladding 18 through the first sleeve 15, and is discharged through the second sleeve 13 and the gas back pressure valve 12. By repeating the charging and discharging operation, the internal pressure change of the simulation cladding 18 can be adjusted, and the internal pressure creep behavior under transient power conditions can be simulated.

[0055] The heating rod 16 provided with several ring ridges 20 and the pressure supply system described above can simulate the stress change of the coated cladding. The following Figure 2 The high-temperature and high-pressure water loop system for simulating the external chemical corrosion of the coated cladding is described.

[0056] The high-temperature and high-pressure water loop system is used to provide a high-temperature and high-pressure water environment simulating the primary loop of the pressurized water reactor, and the simulation cladding 18 is located in the high-temperature and high-pressure water environment.

[0057] The high-temperature and high-pressure water loop system includes a material storage tank 1, a high-pressure pump 2, a heating assembly, and a high-pressure kettle 5. The material storage tank 1 is used to store a water solution simulating the water chemical environment of the primary loop of the pressurized water reactor. The high-pressure pump 2 is used to transport the water solution and apply the required pressure to the water solution, and the inlet of the high-pressure pump 2 is connected to the outlet of the material storage tank 1. The outlet of the high-pressure pump 2 is connected to the inlet of the heating assembly, and the heating assembly heats the pressurized water solution. The high-pressure kettle 5 is used to contain the pressurized and heated water solution and isolate it from the outside, providing a high-temperature and high-pressure water environment simulating the primary loop of the pressurized water reactor. The inlet of the high-pressure kettle 5 is connected to the outlet of the heating assembly, and the simulation cladding 18 is immersed in the high-temperature and high-pressure water solution in the high-pressure kettle 5. A temperature monitoring element is installed in the high-pressure kettle 5 for monitoring the temperature of the water solution in the high-pressure kettle 5.

[0058] In some embodiments, the heating assembly comprises a preheating device 3 and a heat exchange device 4. The preheating device 3 is used to preheat the pressurized water solution, and the inlet of the preheating device 3 is connected to the outlet of the high-pressure pump 2. The heat exchange device 4 is used to heat the pressurized water solution by using the heat of the discharged solution of the autoclave. The cold end inlet of the heat exchange device 4 is connected to the outlet of the preheating device 3, the cold end outlet of the heat exchange device 4 is connected to the inlet of the autoclave 5, and the outlet of the autoclave 5 is connected to the hot end inlet of the heat exchange device 4. Since the heating rod 16 continuously heats the water solution in the autoclave 5 through the simulated cladding 18, the temperature of the water solution discharged from the autoclave 5 (hereinafter referred to as "discharged solution") is higher than that of the preheated water solution, and the heat exchange device 4 plays a regenerative role. In the heat exchange device 4, the preheated water solution exchanges heat with the discharged solution of the autoclave 5, re-heats the preheated water solution, and thus improves the thermal efficiency of the system.

[0059] In some embodiments, the high-temperature and high-pressure water loop system further comprises a cooling device 7 (such as an air cooler) and a water treatment device 9. The cooling device 7 is used to cool the discharged solution after being regenerated, and the inlet of the cooling device 7 is connected to the hot end outlet of the heat exchange device 4. The outlet of the cooling device 7 is communicated with the inlet of the material storage tank 1 through the water treatment device 9, and the water treatment device 9 is used to treat the cooled discharged solution. The water treatment device 9 treats the cooled discharged solution and returns part of it to the material storage tank 1 for recycling, thus completing the simulation of the primary loop water circulation.

[0060] In some embodiments, a liquid back pressure valve 8 is arranged on the flow path between the hot end outlet of the heat exchange device 4 and the inlet of the material storage tank 1, and the liquid back pressure valve 8 is used to maintain the pressure balance of the high-temperature and high-pressure water loop system. Specifically, as shown in Figure 2 the liquid back pressure valve 8 is located between the cooling device 7 and the water treatment device 9, and the liquid back pressure valve 8 can maintain the pressure balance of the system to ensure that the cooled fluid can smoothly enter the water treatment device 9.

[0061] By coupling the high-temperature and high-pressure water environment provided by the high-temperature and high-pressure water loop system and the stress change simulated by the heating rod 16 and the pressure supply system, the test device of the coated cladding involved in the embodiments of the present specification can simulate the local nucleate boiling phenomenon induced by the surface crack of the fuel rod in the high-temperature and high-pressure water environment, so as to test the performance of the coated cladding in the coupling scenario of the high-temperature and high-pressure water environment and the internal stress change.

[0062] A specific embodiment is given below, which is intended to illustrate the implementation of the present application in combination with the above embodiments, and does not limit the application scenarios of the present application.

[0063] The simulated cladding with chromium coating is sleeved on the heating rod as a simulated fuel rod, and a closed cavity is formed in the simulated cladding. A small air gap (about 0.1 mm) is maintained between the simulated cladding and the heating rod to simulate the actual pellet-cladding gap.

[0064] Before the test, the coating integrity is checked to confirm no obvious defects. The initial cladding surface morphology and coating thickness distribution are recorded. The high pressure pump is started to establish a high temperature and high pressure water environment, and is stably operated for 24 hours; the heating rod is started to heat, and is gradually heated to the rated heat load (corresponding to linear power 45 kW / m) according to the power gradient; the internal pressure circulation is started synchronously: the pressure pulse of 0→12 MPa→0 is applied once every 24 hours, and lasts for 100 days (100 cycles in total). The simulated cladding internal pressure is detected in real time. If abnormal pressure fluctuation of the simulated cladding internal pressure is monitored, it indicates that the cladding tube has been damaged, and the test is immediately stopped.

[0065] Test results: water quality monitoring shows that the concentration of Ni and Fe ions in the loop gradually rises, and brown deposits are observed in the crack area of the coating since the 60th day, forming a CRUD scale layer. EIS data shows that the charge transfer resistance in the crack area decreases by 40%, indicating that the corrosion under the scale is accelerated. After the 85th cycle, the simulated cladding internal pressure is abnormal, indicating that the cladding has been damaged, and the test is ended for inspection. The simulated fuel rod is immersed in water, and the pressurized bubbling method is used to locate the damage position, and samples are taken at the damage position for the following microstructure analysis:

[0066] 1) Metallographic and scanning electron microscope observation of the cross section at the damage position shows fatigue and corrosion cracking characteristics, CRUD scale deposition near the crack, and hydride aggregation inside;

[0067] 2) EDS and XRD analysis further clarifies the CRUD composition and crystal structure.

[0068] The above specific embodiments prove the feasibility of the device.

[0069] The above has described the basic concepts, and it is obvious that the above detailed disclosure is only taken as an example for the person skilled in the art, and does not constitute a limitation on the specification. Although some currently considered useful embodiments of the invention are discussed in the above disclosure through various examples, it should be understood that such details are only for illustration purposes, and the additional claims are not limited to the disclosed embodiments, on the contrary, the claims are intended to cover all modifications and equivalent combinations that meet the spirit and scope of the embodiments.

Claims

1. A coated test device characterized by, The test device comprises: a simulation cladding located in a high-temperature and high-pressure water environment, an outer wall of the simulation cladding being coated with a coating layer, the simulation cladding defining a sealed cavity, an internal pressure of the cavity being adjustable; a heating rod arranged in the cavity of the simulation cladding, a plurality of annular ridges being arranged on the heating rod, the annular ridges being arranged at intervals in an axial direction of the heating rod and annularly protruding in a radial direction of the heating rod; wherein an outermost annular surface of the annular ridges in the radial direction is in contact with an inner wall of the simulation cladding, and a through hole is arranged on the annular ridges, the through hole penetrating through opposite sides of the annular ridges in the axial direction to keep the internal pressure of the cavity uniform.

2. The test device of the coated capsule of claim 1, wherein, The simulation cladding is in a tubular structure and coaxially arranged with the heating rod.

3. The coated capsule testing device of claim 1, wherein, Axial distances between adjacent annular ridges on the heating rod are close or consistent.

4. The coated capsule testing device of claim 1, wherein, The through hole also penetrates the annular surface of the annular ridges located at the outermost side in the radial direction.

5. The test device of the coated capsule of claim 1, wherein, The test device comprises a pressure supply system for inflating or deflating the cavity of the simulation cladding to simulate an internal pressure creep state in a fuel rod heating process.

6. The test device of the coated capsule of claim 5, wherein, An air inlet and an air outlet are arranged on the simulation cladding, and the air inlet and the air outlet are both in communication with the cavity; The pressure supply system comprises a gas source and a booster pump, the gas source is connected with the air inlet through the booster pump to realize air inflation and pressure increase, and a gas back pressure valve is arranged at the air outlet to realize stable air exhaust.

7. The test device of the coated capsule of claim 1, wherein, The test device comprises a high-temperature and high-pressure water loop system for providing a high-temperature and high-pressure water environment simulating a primary loop of a pressurized water reactor.

8. The test device of the coated capsule of claim 7, wherein, The high-temperature and high-pressure water loop system comprises: a material storage tank for storing a water solution simulating a water chemical environment of a pressurized water reactor primary loop fouling deposition; a high-pressure pump for pressurizing the water solution, an inlet of the high-pressure pump being connected with an outlet of the material storage tank; a heating assembly for heating the pressurized water solution, an inlet of the heating assembly being connected with an outlet of the high-pressure pump; a high-pressure kettle for containing the pressurized and heated water solution and isolating it from the outside to provide the high-temperature and high-pressure water environment, an inlet of the high-pressure kettle being connected with an outlet of the heating assembly, and the simulation cladding being placed in the water solution in the high-pressure kettle.

9. The test device of the coated capsule of claim 8, wherein, The heating assembly comprises: a preheating device for preheating the pressurized water solution, an inlet of the preheating device being connected with an outlet of the high-pressure pump; a heat exchange device for heating the pressurized water solution by using heat of discharged liquid of the high-pressure kettle, a cold end inlet of the heat exchange device being connected with an outlet of the preheating device, a cold end outlet of the heat exchange device being connected with an inlet of the high-pressure kettle, and an outlet of the high-pressure kettle being connected with a hot end inlet of the heat exchange device.

10. The test device of the coated capsule of claim 9, wherein, The high-temperature and high-pressure water loop system further comprises a cooling device and a water treatment device, the cooling device being used for cooling the discharged liquid, an inlet of the cooling device being connected with a hot end outlet of the heat exchange device, and an outlet of the cooling device being in communication with an inlet of the material storage tank through the water treatment device, the water treatment device being used for treating the cooled discharged liquid.

11. The test device of the coated capsule of claim 10, wherein, A liquid back pressure valve is provided in the flow path between the hot end outlet of the heat exchange device and the inlet of the material storage tank, and is used to maintain pressure balance of the high temperature and high pressure water loop system.

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