Apparatus and method for simulating cladding tube rupture of a fuel assembly under accident conditions

Abstract

The embodiment of the application relates to the technical field of testing of nuclear reactors, in particular to a device and method for simulating breakage of a cladding tube of a fuel assembly under an accident condition, the device comprising an environment simulation assembly, a fuel assembly simulation piece and a breakage determination piece; the fuel assembly simulation piece is arranged in the environment simulation assembly and is used for simulating the fuel assembly and is arranged to be capable of simulating breakage of the cladding tube of the fuel assembly under a reactor accident condition; the environment simulation assembly is arranged to be capable of simulating a core environment in which the fuel assembly is located under the reactor accident condition and is capable of simulating flow of a coolant in the reactor through the fuel assembly simulation piece; and the breakage determination piece is used for determining the breakage of the cladding tube of the fuel assembly simulation piece under the accident condition. The embodiment of the application simulates the core environment in which the fuel assembly is located under the reactor accident condition and simulates the breakage of the cladding tube of the fuel assembly under the reactor accident condition, so that the actual situation of the fuel assembly under the reactor accident condition can be accurately obtained.

Description

Technical Field

[0001] The embodiments of this application relate to the field of nuclear reactor testing technology, and in particular to an apparatus and method for simulating the cladding tube of a fuel assembly rupture under accident conditions. Background Technology

[0002] This section is only intended to provide background information relevant to this application and does not necessarily constitute prior art.

[0003] During the operation of a nuclear power plant reactor, the performance of the nuclear fuel is a crucial factor affecting the reactor's safety and economic efficiency. Therefore, before the fuel assemblies are put into formal use, various tests need to be conducted to promote the development of nuclear power in a safer and more economical direction.

[0004] Typically, before placing fuel assemblies into the reactor for irradiation testing, their physical properties, thermo-hydraulic properties, and other characteristics need to be tested. Currently, there are shortcomings in the technology for testing fuel assemblies. Summary of the Invention

[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] In a first aspect, embodiments of this application provide an apparatus for simulating the cladding tube of a fuel assembly rupture under accident conditions, comprising: an environmental simulation component, a fuel assembly simulator, and a rupture determination component; the fuel assembly simulator is disposed on the environmental simulation component, used to simulate a fuel assembly, and configured to simulate the thermal rupture of the cladding tube of the fuel assembly under reactor accident conditions; the environmental simulation component is configured to simulate the core environment in which the fuel assembly is located under reactor accident conditions, and to simulate the flow of coolant within the reactor through the fuel assembly simulator; the rupture determination component is used to determine the thermal rupture condition of the cladding tube simulated by the fuel assembly simulator.

[0007] Secondly, embodiments of this application provide a method for simulating fuel assembly failure under accident conditions, which is implemented using the apparatus provided in the first aspect of this application.

[0008] The embodiments of this application simulate the core environment of fuel assemblies under reactor accident conditions by setting up an environmental simulation component. Fuel assembly simulators are used to simulate fuel assemblies and simulate the thermal damage of cladding tubes under reactor accident conditions, which is more conducive to accurately obtaining the actual situation of fuel assemblies under reactor accident conditions. In addition, by setting up a damage determination component to determine the thermal damage of cladding tubes simulated by the fuel assembly simulator, it is easier to understand the damage status of cladding tubes more timely.

[0009] These and other advantages of this application will become more apparent from the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0010] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are indicated by the same reference numerals. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.

[0011] Figure 1 This is a schematic diagram of a device for simulating the damage of the cladding tube of a fuel assembly under accident conditions, according to an embodiment of this application. Figure 2 This is a schematic diagram of the structure of a fuel element simulator according to an embodiment of this application; Figure 3 yes Figure 2 The diagram shows the structure of the first dissimilar metal connector. Figure 4 yes Figure 2 The diagram shows the structure of the second dissimilar metal connector.

[0012] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding.

[0013] Explanation of reference numerals in the attached figures: 100. Environmental simulation component; 10. Sealed container; 11. First pipe section; 12. Second pipe section; 13. Third pipe section; 131. Upper pipe section; 132. Corrugated pipe; 133. Lower pipe section; 134. First extension section; 135. Second extension section; 14. First cover; 15. Second cover; 16. Mounting component; 101. Air inlet; 102. Air outlet; 103. Drainage outlet; 104. Resin injection outlet; 105. Resin overflow outlet; 106. Temperature sensor lead wire outlet; 20. Fuel element simulator; 201. Positioning simulator; 21. Sheathed tube simulation component; 22. Electric heating component; 221. Heated section; 222. Non-heated section; 23. First dissimilar metal connector; 231. First connector; 232. Second connector; 2321. Second connector body; 2322. Second mating section; 24. Second dissimilar metal connector; 241. Third connector; 2411. Third connector body; 2412. Third insertion section; 242. Fourth connector; 2421. Fourth connector body; 2422. Fourth connection section; 25. Inflatable component; 26. Insulating end; 27. Lead wire; 30. Definitely damaged parts; 40. Inert gas supply components. Detailed Implementation

[0014] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0015] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0016] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning as understood by a person with ordinary skills in the field to which this application pertains.

[0017] In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0018] Currently, when testing fuel assemblies, the possibility that damage to the cladding tubes under accident conditions could alter the flow channels within the fuel assembly, thereby affecting the flow of coolant within the fuel assembly is not taken into account.

[0019] To address the aforementioned technical problems, embodiments of this application provide a device for simulating the rupture of a fuel assembly's cladding tube under accident conditions (hereinafter referred to as the simulation device).

[0020] See Figure 1 , Figure 1 This is a schematic diagram of a device for simulating the cladding tube of a fuel assembly under accident conditions, according to an embodiment of this application. The simulation device provided in this embodiment includes: an environmental simulation component 100, a fuel assembly simulator, and a damage determination component 30. The fuel assembly simulator is disposed in the environmental simulation component 100 and is used to simulate the fuel assembly and is configured to simulate the thermal damage of the cladding tube of the fuel assembly under reactor accident conditions. The environmental simulation component 100 is configured to simulate the core environment in which the fuel assembly is located under reactor accident conditions and to simulate the flow of coolant through the fuel assembly simulator within the reactor. The damage determination component 30 is used to determine the thermal damage condition of the cladding tube simulated by the fuel assembly simulator.

[0021] The embodiments of this application simulate the core environment of fuel assemblies under reactor accident conditions by setting up an environmental simulation component 100. Fuel assembly simulators are used to simulate fuel assemblies and simulate the thermal damage of cladding tubes under reactor accident conditions, which is more conducive to accurately obtaining the actual situation of fuel assemblies under reactor accident conditions. In addition, by setting up a damage determination component 30 to determine the thermal damage of cladding tubes simulated by the fuel assembly simulator, it is easier to understand the damage situation of cladding tubes more timely.

[0022] In some embodiments, the fuel assembly simulator includes: a plurality of fuel element simulators 20 and a positioning simulator 201; the fuel element simulators 20 are used to simulate the fuel elements of the fuel assembly; the positioning simulator 201 is used to simulate the positioning grid of the fuel assembly to position the plurality of fuel element simulators 20 in the environmental simulation assembly 100. In such an embodiment, the positioning simulator 201 positions the plurality of fuel element simulators 20 in the environmental simulation assembly 100, preventing the fuel element simulators 20 from moving radially and ensuring that the flow channels between adjacent fuel element simulators 20 are relatively fixed, thereby simulating a real fuel assembly.

[0023] In some embodiments, the plurality of fuel element simulators 20 may be arranged in an array.

[0024] See Figure 2 , Figure 2This is a schematic diagram of a fuel element simulator according to one embodiment of this application. In some embodiments, the fuel element simulator 20 includes: a casing tube simulator 21, an electric heating element 22, and an inflation element 25. The casing tube simulator 21 is used to simulate the casing tube of a fuel element; the electric heating element 22 is used to simulate the heating of the fuel pellets of the fuel element; the inflation element 25 is configured to fill the casing tube simulator 21 with gas and maintain the interior of the casing tube simulator 21 at a preset pressure when the electric heating element 22 is not heating, so as to simulate the gas environment inside the fuel element in its initial state. The damage determination element 30 is also configured to measure the pressure of the inflation element 25 to determine the thermal damage condition of the casing tube simulator 21.

[0025] In this embodiment, by providing the inflation component 25, the interior of the fuel element simulation component 20 can be made to have the same gaseous environment as the fuel element in its initial state by inflating the cladding tube simulation component 21; by providing the electric heating component 22, the continuous heating of the fuel pellet can be simulated, so that the material of the cladding tube simulation component 21 melts and softens after being heated, and breaks under internal pressure; the breakage determination component 30 can measure the internal pressure change of the fuel element simulation component 20 through the inflation component 25, thereby obtaining the thermal breakage condition of the cladding tube simulation component 21.

[0026] Specifically, as the electric heating element 22 continues to heat up, the pressure inside the shell tube simulation element 21 gradually increases until the shell tube simulation element 21 breaks, and the pressure inside the shell tube simulation element 21 drops sharply. Therefore, by measuring the pressure change inside the shell tube simulation element 21, the damage status of the shell tube simulation element 21 can be determined.

[0027] In some embodiments, the inflation member 25 can be a thin tube with a connector, one end of which is welded to the first dissimilar metal connector 23 and the other end is connected to the Swagelok connector, thereby enabling the internal pressure of the casing tube simulator 21.

[0028] In some embodiments, the heating section 221 of the electric heating element 22 is located inside the sealed container 10, and the non-heating section 222 extends from inside the sealed container 10 to the outside.

[0029] In some embodiments, the metal material forming the casing tube simulator 21 is different from the metal material forming the shell of the electric heating element 22 and the metal material forming the inflation element 25; the fuel element simulator 20 further includes: a first dissimilar metal connector 23 and a second dissimilar metal connector 24; the first dissimilar metal connector 23 is welded to the shell of the electric heating element 22 to seal one side of the casing tube simulator 21; the inflation element 25 is welded to the second dissimilar metal connector 24, and the second dissimilar metal connector 24 is welded to the casing tube simulator 21. Since the material of the casing tube simulator 21 is different from the materials of the electric heating element 22 and the inflation element 25, the first dissimilar metal connector 23 and the second dissimilar metal connector 24 are provided to improve the welding effect and enhance the sealing performance.

[0030] In some embodiments, the metal material forming the cladding tube simulation component 21 may be a zirconium alloy; the metal material forming the shell of the electric heating component 22 and the metal material forming the inflation component 25 may be stainless steel.

[0031] Figure 3 yes Figure 2 The diagram shows the structure of the first dissimilar metal connector; see also Figure 3 The first dissimilar metal connector 23 may include a first connector 231 and a second connector 232 connected to the first connector 231; the material of the first connector 231 is the same as the material of the shell of the electric heating element 22, and it is used to weld to the shell of the electric heating element 22; the material of the second connector 232 is the same as the material of the shell tube simulation component 21, and it is used to weld to the shell tube simulation component 21 to improve the welding effect and avoid air leakage at the weld when the internal pressure of the shell tube simulation component 21 is high.

[0032] The first connector 231 can be corner welded to the housing of the electric heating element 22.

[0033] In some embodiments, the second connector 232 includes a second connector body 2321 and a second mating section 2322. The second connector body 2321 is connected to the first connector 231, and the second mating section 2322 is used for butt welding with the cladding tube simulation component 21 to further improve the welding effect.

[0034] Figure 4 yes Figure 2 The diagram shows the structure of the second dissimilar metal connector. (See attached diagram.) Figure 4 The second dissimilar metal connector 24 may include a third connector 241 and a fourth connector 242. The material of the third connector 241 is the same as that of the shell tube simulator 21, and it is used for welding the shell tube simulator 21. The material of the fourth connector 242 is the same as that of the inflator 25, and it is used for welding with the inflator 25 to improve the welding effect.

[0035] In some embodiments, the third connector 241 includes a third connector body 2411 and a third insertion segment 2412, and the fourth connector 242 includes a fourth connector body 2421 and a fourth connector segment 2422. The third connector body 2411 is connected to the fourth connector body 2421, and the third insertion segment 2412 enters the cladding tube simulation component 21 and is socket-welded to the cladding tube simulation component 21. The inflation component 25 enters the fourth connector segment 2422 and is socket-welded to the fourth connector segment 2422 to further improve the welding effect.

[0036] In some embodiments, the environmental simulation component 100 includes: a sealed container 10, an air inlet 101, and an air outlet 102; a fuel assembly simulator is disposed within the sealed container 10, and an inflation member 25 of the fuel assembly simulator extends to the outside of the sealed container 10; the sealed container 10 is configured to avoid applying a compressive force to the extending direction of the fuel assembly simulator. Coolant enters the sealed container 10 via the air inlet 101, flows through the fuel assembly simulator, and exits the sealed container 10 via the air outlet 102 to simulate the coolant environment under accident conditions. In such an embodiment, by allowing coolant to enter the sealed container 10 via the air inlet 101 and exit the sealed container 10 via the air outlet 102 after flowing through the fuel assembly simulator, the high-temperature environment of coolant water evaporation and vaporization under accident conditions can be simulated. Since the inflation component 25 of the fuel assembly simulator extends to the outside of the sealed container 10, the failure determination component 30 can measure the pressure of the inflation component 25 at the ambient temperature outside the sealed container 10, and an external gas source can be connected to the inflation component 25 through a pipeline to inject a fixed amount of gas into the inflation component 25 so that the internal pressure of the casing tube simulator 21 is at a preset pressure before the electric heating component 22 is heated, so as to simulate the gas environment inside the fuel element.

[0037] Under high temperature conditions, the sealed container 10 and the fuel assembly simulator will expand due to heat, but the degree of expansion of the two is different. In order to avoid the sealed container 10 applying a compressive force along the length direction to the fuel assembly simulator after the temperature rises, which would affect the deformation and damage of the fuel assembly simulator and thus fail to realistically simulate the deformation and damage of the fuel element under accident conditions, the embodiments of this application configure the sealed container 10 to avoid applying a compressive force to the extension direction of the fuel assembly simulator, thereby facilitating a more realistic simulation of the deformation and damage of the fuel element under accident conditions.

[0038] In some embodiments, the sealing container 10 is configured to extend and retract along the extension direction of the fuel assembly simulator to accommodate the length of the fuel element simulator 20. By extending and retracting the sealing container 10, the length of the fuel element simulator 20 can be accommodated after thermal expansion, preventing the sealing container 10 from exerting a compressive force on the extension direction of the fuel element simulator 20.

[0039] In some embodiments, the environmental simulation component 100 further includes a resin injection port 104 and a resin overflow port 105. The resin injection port 104 is used to add resin into the sealed container 10 after the casing tube simulation component 21 of the fuel assembly simulation component bursts and the temperature drops to a preset temperature. The resin overflow port 105 is used to allow the resin in the sealed container 10 to overflow outward after filling to a height higher than the casing tube simulation component 21. In such an embodiment, by providing the resin injection port 104 and the resin overflow port 105, resin can be added to the sealed container 10, thereby allowing the fuel assembly simulation component to maintain its current state. After the fuel assembly simulation component is removed from the sealed container 10, it is convenient to directly perform relevant tests.

[0040] In some embodiments, the sealed container 10 includes: a first pipe segment 11, a second pipe segment 12, a third pipe segment 13, a first cover 14, and a second cover 15; the first pipe segment 11 and the third pipe segment 13 are detachably and sealingly connected to the second pipe segment 12 at both ends, respectively; the second pipe segment 12 is configured to cooperate with an external structure to be supported by the external structure; the third pipe segment 13 is configured to be axially telescopic; the first cover 14 and the second cover 15 are detachably and sealingly connected to the first pipe segment 11 and the third pipe segment 13, respectively, for closing the openings of the first pipe segment 11 and the third pipe segment 13 facing away from the second pipe segment 12.

[0041] In such an embodiment, the first cover 14 can be removed from the first pipe section 11, the first pipe section 11 can be removed from the second pipe section 12, and the second cover 15 can be removed from the third pipe section 13, and the third pipe section 13 can be removed from the second pipe section 12, thereby removing the resin-cured fuel assembly simulator entirely from the second pipe section 12.

[0042] In some embodiments, the first cover 14 is provided with a plurality of first through holes, and each inflatable member 25 extends outward from the first through hole of the first cover 14 so as to position each inflatable member 25 by the first cover 14; in some embodiments, the second cover 15 is provided with a plurality of second through holes, and the insulating end 26 of each electric heating member 22 is disposed in the second through hole of the second cover 15, and the lead wire 27 extends outward from the second cover 15 so as to position each insulating end 26 by the second cover 15.

[0043] In some embodiments, the second pipe segment 12 is provided with a mounting member 16 for cooperating with an external structure to install the second pipe segment 12 onto the external structure and to enable the second pipe segment 12 to be supported by the external structure.

[0044] In some embodiments, the third pipe section 13 may include an upper pipe section 131, a lower pipe section 133, and a corrugated pipe 132 connecting the upper pipe section 131 and the lower pipe section 133, thereby achieving the overall contraction of the third pipe section 13 through the expansion and contraction of the corrugated pipe 132. In some embodiments, the third pipe section 13 may include a first extension section 134 and a second extension section 135, which are respectively connected to the upper pipe section 131 and the lower pipe section 133. The first extension section 134 and the second extension section 135 are slidably engaged to provide thermal shielding for the corrugated pipe 132, preventing steam from adversely affecting the corrugated pipe 132.

[0045] In some embodiments, the coolant is water vapor, and the environmental simulation component 100 includes a drain port 103 for discharging condensate from the sealed container 10. In the initial stage of water vapor entering the sealed container 10, pre-cooling of the water vapor forms condensate, which is discharged to the outside of the sealed container 10 through the drain port 103. Once the interior of the sealed container 10 is entirely filled with water vapor, the fuel element simulation component 20 is then self-heated.

[0046] In some embodiments, the simulation device further includes a temperature measuring element for measuring the temperature of the fuel element simulation element 20, thereby controlling the heating rate of the electric heating element 22 based on the measured temperature to simulate the heating of the fuel element under accident conditions.

[0047] In some embodiments, the temperature probe of the temperature measuring element is fixed to the outer wall of the cladding tube simulator 21 of the fuel element simulator 20 to measure the temperature of the cladding tube simulator 21. The heating rate of the electric heating element 22 is then controlled based on the measured temperature of the cladding tube simulator 21 to more accurately simulate the temperature rise of the fuel element under accident conditions.

[0048] In some embodiments, the environmental simulation component 100 further includes a temperature sensing element lead wire interface 106 for leading the temperature sensing element out of the sealed container 10 of the environmental simulation component 100 to transmit the detected temperature signal to the outside.

[0049] In some embodiments, the air inlet 101 and the resin injection 104 are disposed in the first pipe section 11; the air outlet 102 and the resin overflow 105 are disposed in the third pipe section 13. The temperature sensing element wire interface 106 is disposed in the second pipe section 12.

[0050] In some embodiments, the failure determination element 30 is a pressure measuring element configured to measure the pressure inside the cladding tube simulator 21 in the fuel assembly simulator, so as to determine the thermal failure of the cladding tube simulator 21 based on the pressure inside the cladding tube simulator 21.

[0051] In some embodiments, the simulation apparatus may further include an inert gas supply 40 for supplying inert gas to the inflation member 25.

[0052] In some embodiments, the simulation apparatus may further include a coolant supply for supplying high-temperature steam to the sealed container 10.

[0053] Embodiments of this application also provide a method for simulating fuel assembly failure under accident conditions, which is implemented using the apparatus provided in any embodiment of this application.

[0054] In some embodiments, the method includes the following steps: S1, providing a circulating coolant to the environmental simulation component to simulate the core environment of the fuel assembly under reactor accident conditions; S2, continuously heating the fuel assembly simulator to simulate the continuous heating of the fuel elements of the fuel assembly under reactor accident conditions, resulting in thermal damage to the cladding tubes; S3, determining the thermal damage status of the cladding tubes simulated by the fuel assembly simulator; S4, after the fuel assembly simulator simulates all cladding tubes undergoing thermal damage, stopping the heating of the fuel assembly simulator and allowing the fuel assembly simulator to cool down.

[0055] The embodiments of this application simulate the core environment of fuel assemblies under reactor accident conditions by setting up an environmental simulation component. Fuel assembly simulators are used to simulate fuel assemblies and simulate the thermal damage of cladding tubes under reactor accident conditions, which is more conducive to accurately obtaining the actual situation of fuel assemblies under reactor accident conditions. In addition, by setting up a damage determination component to determine the thermal damage of cladding tubes simulated by the fuel assembly simulator, it is easier to understand the damage status of cladding tubes more timely.

[0056] In some embodiments, step S4 specifically includes the following steps: S41, after the simulation ends, stop heating the fuel assembly simulator and allow it to cool naturally to a preset temperature; S42, provide circulating cooling water to the environmental simulation assembly to simulate flushing water into the reactor core to cool it after a reactor accident. In such embodiments, the actual operating conditions of the reactor can be simulated more realistically, thereby obtaining a more accurate cladding tube damage status to determine the impact on the flow channels of the fuel assembly.

[0057] In some embodiments, the method further includes: S5, injecting a curing material into the environmental simulation component to maintain the fuel assembly simulator in its current state after the curing material solidifies; S6, removing the fuel assembly simulator from the environmental simulation component. In such embodiments, it is convenient to maintain the fuel assembly simulator in its current state even in the event of simulated thermal damage to the cladding tube, thereby facilitating subsequent testing.

[0058] In some embodiments, the method further includes, before step S1: S0, filling the fuel element simulator with inert gas to make the internal environment of the fuel element simulator the same as that of a real fuel element, thereby improving the accuracy of the simulation results.

[0059] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0060] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A device for simulating the rupture of a fuel assembly's cladding tube under accident conditions, characterized in that, include: Environmental simulation components, fuel assembly simulation components, and damage determination components; The fuel assembly simulator is disposed on the environmental simulation assembly. The fuel assembly simulator is used to simulate a fuel assembly and is configured to simulate the cladding tubes of the fuel assembly being damaged by heat under reactor accident conditions. The environmental simulation component is configured to simulate the reactor core environment in which the fuel assembly is located under reactor accident conditions, and to simulate the flow of coolant through the fuel assembly simulator within the reactor. The damage determination component is used to determine the thermal damage of the cladding tube simulated by the fuel assembly simulator.

2. The apparatus according to claim 1, characterized in that, The fuel assembly simulator includes: Multiple fuel element simulators, each of which is used to simulate a fuel element of the fuel assembly; A positioning simulator is used to simulate the positioning grid of the fuel assembly for positioning the plurality of fuel element simulators within the environmental simulation assembly.

3. The apparatus according to claim 2, characterized in that, The fuel element simulator includes: A casing tube simulator, used to simulate the casing tube of the fuel element; An electric heating element is used to simulate the heating of the fuel pellets in the fuel element; The inflation component is configured to inflate gas into the cladding tube simulator and maintain the interior of the cladding tube simulator at a preset pressure when the electric heating component is not heated, so as to simulate the gas environment inside the fuel element in its initial state. The damage determination device is also configured to measure the pressure of the inflatable component to determine the thermal damage condition of the casing tube simulation component.

4. The apparatus according to claim 3, characterized in that, The metal material forming the cladding tube simulation component is different from the metal material forming the shell of the electric heating component or the metal material forming the inflatable component; The fuel element simulator also includes: First dissimilar metal connector and second dissimilar metal connector; The first dissimilar metal connector is welded to the housing of the electric heating element to seal one side of the cladding tube simulation component; The inflatable component is welded to the second dissimilar metal connector, and the second dissimilar metal connector is welded to the shell tube simulation component.

5. The apparatus according to claim 1, characterized in that, The environment simulation component includes: A sealed container, wherein the fuel assembly simulator is disposed within the sealed container, and the inflation component of the fuel assembly simulator extends to the outside of the sealed container; the sealed container is configured to prevent the application of compressive forces to the extending direction of the fuel assembly simulator. The system includes an air inlet and an air outlet. Coolant enters the sealed container through the air inlet and exits the sealed container through the air outlet after passing through the fuel assembly simulator, thus simulating the coolant environment under accident conditions.

6. The apparatus according to claim 5, characterized in that, The sealed container is configured to extend and retract along the extension direction of the fuel assembly simulator to accommodate the length of the fuel assembly simulator.

7. The apparatus according to claim 5, characterized in that, The environment simulation component also includes: The system includes a resin injection port and a resin overflow port. The resin injection port is used to add resin into the sealed container after the casing tube of the fuel assembly simulator ruptures and the temperature drops to a preset temperature. The resin overflow port is used to allow resin from the sealed container to overflow outwards after filling it to a height higher than the cladding tube simulation component.

8. The apparatus according to claim 7, characterized in that, The sealed container includes: First pipe section, second pipe section, third pipe section, first cover and second cover; The first pipe segment and the third pipe segment are respectively detachably and sealingly connected to the second pipe segment at both ends; The second pipe section is configured to fit with an external structure so that the external structure can provide support; The third pipe section is configured to extend and retract axially. The first cover and the second cover are detachably and sealingly connected to the first pipe segment and the third pipe segment, respectively, to close the openings of the first pipe segment and the third pipe segment facing away from the second pipe segment.

9. The apparatus according to claim 2, characterized in that, Also includes: A temperature measuring element is used to measure the temperature of the fuel element simulator.

10. The apparatus according to claim 9, characterized in that, The temperature measuring probe of the temperature measuring element is fixed to the outer wall of the casing tube of the fuel element simulation element; The environment simulation component also includes: A wire interface for the temperature sensor, used to allow the wires of the temperature sensor to be led out of the sealed container of the environmental simulation component.

11. The apparatus according to any one of claims 1-10, characterized in that, The damage determination device is a pressure measuring device, configured to measure the pressure inside the cladding tube simulator in the fuel assembly simulator, so as to determine the thermal damage of the cladding tube simulator based on the pressure inside the cladding tube simulator.

12. A method for simulating the rupture of a fuel assembly's cladding tube under accident conditions, characterized in that, The method is implemented using the apparatus described in any one of claims 1-11.

13. The method according to claim 12, characterized in that, It includes the following steps: S1. Provide circulating coolant to the environmental simulation component to simulate the core environment of the fuel assembly under reactor accident conditions; S2. Continuously heat up the fuel assembly simulator to cause the cladding tube simulator of the fuel assembly simulator to break due to heat, so as to simulate the cladding tube breaking due to heat when the fuel element of the fuel assembly continues to heat up under the reactor accident condition. S3. Determine the heat damage condition of the cladding tube simulated by the fuel assembly simulator; S4. Once the fuel assembly simulator simulates all the cladding tubes being damaged by heat, stop heating the fuel assembly simulator and allow it to cool down.

14. The method according to claim 13, characterized in that, Step S4 specifically includes the following steps: S41. After the simulation ends, stop heating the fuel assembly simulator and allow it to cool naturally to the preset temperature. S42. Provide circulating cooling water to the environmental simulation component to simulate flushing water into the reactor core to cool the core after a reactor accident.

15. The method according to claim 13, characterized in that, Also includes: S5. Inject curing material into the environmental simulation component so that the fuel assembly simulator remains in its current state after the curing material solidifies; S6. Remove the fuel assembly simulator from the environment simulation assembly.

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