Sample loading device for nuclear fuel cladding simulation test and method of using the same

Abstract

The application discloses a kind of nuclear fuel cladding simulation test loading device and its using method, loading device includes support main body, support component, push rod and temperature measuring tube;Support component is connected in the first side of support main body, and support component is formed with support position;Push rod is worn on support main body and parallel with support component;The first end of push rod is in the first side of support main body and opposite with support position, and the second end opposite with push rod is in the second side of support main body;Push rod is movable in axial direction relative to support main body;Temperature measuring tube is worn on support main body and parallel with support component.The application is stable by the cooperation of support main body, support component, push rod and temperature measuring tube, and supports cladding sample when high-temperature steam oxidation, guarantees that cladding sample is in full contact with high-temperature steam, and completely sufficient oxidation;Push rod is used to push cladding sample before quenching thermal shock, and guarantees that cladding sample is quickly separated from loading device and falls into cooling water pool to complete thermal shock process.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel cladding test equipment technology, and in particular to a nuclear fuel cladding simulation test sample loading device and its usage method. Background Technology

[0002] A loss-of-coolant accident (LOCA) at a nuclear power plant refers to an accident caused by a breach in the primary circuit boundary of a nuclear reactor, leading to a rapid loss of coolant. It is one of the design basis accidents for nuclear power plants. After a LOCA accident, the temperature of the nuclear fuel cladding rises rapidly and it oxidizes rapidly in a high-temperature steam environment. After the high-temperature steam oxidation of the nuclear fuel cladding continues for a period of time, the emergency core cooling system is activated and safety injection water is injected into the core. The temperature of the nuclear fuel cladding begins to drop under the influence of the low-temperature steam at the cooling front of the safety injection water. When the safety injection water submerges the core (~800°C), the fuel rods are quenched by the cooling water, causing a sharp drop in the temperature of the nuclear fuel cladding, thus completing the high-temperature steam oxidation thermal shock process of the nuclear fuel cladding.

[0003] Under a Loss-of-Water (LOCA) accident, nuclear fuel cladding undergoes high-temperature steam oxidation and quenching thermal shock loads, which can easily damage the cladding and threaten the safe operation of the reactor. To evaluate the performance of nuclear fuel cladding under a Loss-of-Water (LOCA) accident, a dedicated LOCA-simulated test setup is typically constructed to conduct high-temperature oxidation and quenching thermal shock tests on the fuel rod cladding outside the reactor. Existing methods for high-temperature oxidation and quenching thermal shock testing of fuel rod cladding mainly describe the components, systems, overall integration, and test methods of dedicated test setups for high-temperature oxidation thermal shock testing of nuclear fuel cladding or fuel rod bundles. These methods focus on protecting the overall functionality and test methods for completing the high-temperature oxidation thermal shock test of nuclear fuel cladding, but do not specify the specific type of sample loading device for mounting nuclear fuel cladding samples. For these dedicated high-temperature oxidation thermal shock test setups, the cladding sample loading device is the core component that ensures the sample completes the high-temperature steam oxidation and thermal shock process. It must ensure that the nuclear fuel cladding sample is completely, fully, and uniformly oxidized during the test, with accurate temperature measurement and the ability to complete the thermal shock process. Therefore, a dedicated nuclear fuel cladding sample loading device needs to be designed to ensure the accuracy and success rate of the high-temperature oxidation thermal shock test.

[0004] To improve the fault tolerance of nuclear reactors under accident conditions, a new generation of fuel concept has been proposed: Accident Tolerant Fuel (ATF). SiC composite cladding, as an innovative ATF cladding material, possesses advantages such as high melting point, corrosion resistance, high-temperature oxidation resistance, minimal strength reduction at high temperatures, and no hydrogen production. Research on high-melting-point, oxidation-resistant materials like SiC composite cladding under LOCA accident conditions involves prolonged oxidation in a high-temperature steam environment, ranging from several hours to tens of hours. Therefore, it is necessary to design a specialized sample loading device capable of withstanding ultra-long-term use at high steam oxidation temperatures to conduct high-temperature oxidation thermal shock tests on SiC composite cladding, ensuring successful testing on the first attempt and accurate and reliable results. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a sample loading device for nuclear fuel cladding simulation test and a method for using it.

[0006] The technical solution adopted by the present invention to solve its technical problem is: to provide a sample loading device for a nuclear fuel cladding simulation test, which is used for loading samples for a high-temperature steam oxidation thermal shock test of nuclear fuel cladding. The nuclear fuel cladding simulation test sample loading device includes a support body, a support assembly, a push rod, and a temperature measuring tube. The support assembly is connected to the first side of the support body, and a support position is formed on the support assembly. The support position is used to support the shell sample through point contact. The push rod passes through the support body and is parallel to the support assembly; the first end of the push rod is located on the first side of the support body and is directly opposite the support position, and the opposite second end of the push rod is located on the second side of the support body; the push rod can move back and forth axially relative to the support body to push the shelled sample. The temperature measuring tube is inserted through the support body and parallel to the support assembly. The temperature measuring tube is used for thermocouples to be inserted therethrough to measure the temperature of the encapsulated sample.

[0007] Preferably, the support body includes a support plate and a connecting rod; the support plate has a first surface and a second surface opposite to each other, the first surface of the support plate forms a first side of the support body, and the connecting rod is perpendicularly connected to the second surface of the support plate.

[0008] Preferably, the support body further includes a steam channel that extends through the support plate and the connecting rod.

[0009] Preferably, the support assembly includes two support rods and several V-shaped rods; Two support rods are connected parallel to each other on the first side of the support body; a plurality of V-shaped rods are spaced apart along the axial direction of the support rods and connected between the two support rods, defining a V-shaped support position between the two support rods.

[0010] Preferably, the push rod includes a rod body and an end plate; The rod is inserted through the support body, and the end plate is connected to the first end of the rod and is used to contact the end face of the shelled sample.

[0011] Preferably, the end plate is a circular plate with a diameter greater than or equal to the outer diameter of the shell sample; and / or, the end plate is a perforated plate.

[0012] Preferably, the support body, support components, push rod, and temperature measuring tube are all made of high-temperature oxidation resistant materials.

[0013] Preferably, the nuclear fuel cladding simulation test sample loading device further includes a thermocouple, which is inserted into the temperature measuring tube, and the temperature measuring end of the thermocouple is close to or in contact with the outer surface of the cladding sample.

[0014] The present invention also provides a method for using a sample loading device for simulating nuclear fuel cladding tests, used for high-temperature steam oxidation thermal shock tests of nuclear fuel cladding, the method comprising the following steps: S1. Place the cladding sample to be tested on the support assembly of the nuclear fuel cladding simulation test sample loading device, with the thermocouple's measuring end close to or against the outer surface of the cladding sample, so that the first end of the push rod of the nuclear fuel cladding simulation test sample loading device is close to the support body and away from the cladding sample. S2. The nuclear fuel cladding simulation test loading device with the cladding sample is pushed into the furnace of the high-temperature furnace to perform high-temperature steam oxidation on the cladding sample. S3. After completing the high-temperature steam oxidation, remove the nuclear fuel cladding simulation test sample loading device with the cladding sample from the high-temperature furnace and place it above the quenching water pool. Turn the nuclear fuel cladding simulation test sample loading device over so that the cladding sample falls into the quenching water pool to complete the quenching thermal shock action.

[0015] Preferably, after high-temperature steam oxidation is completed, the push rod is pushed to move the shell sample 1mm to 2mm on the support assembly, so as to prevent the shell sample from sticking to the support assembly.

[0016] The beneficial effects of this invention are as follows: Through the cooperation of the support body, support components, push rod, and temperature measuring tube, the cladding sample can be stably supported during high-temperature steam oxidation, ensuring that the cladding sample is in full contact with the high-temperature steam and can be fully oxidized, preventing test failure due to insufficient steam or incomplete oxidation; the temperature measuring tube, with a thermocouple, ensures real-time and accurate temperature measurement of the cladding sample; the push rod is used to push the cladding sample before the quenching thermal shock, preventing the cladding sample from sticking to the support components and ensuring that the cladding sample quickly detaches from the sample loading device and falls into the cooling water pool to complete the thermal shock process. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the structure of a nuclear fuel cladding simulation test sample loading device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the nuclear fuel cladding simulation test sample loading device according to an embodiment of the present invention after placing the cladding sample; Figure 3 This is a schematic diagram of the supporting main body in a nuclear fuel cladding simulation test sample loading device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the push rod structure in a nuclear fuel cladding simulation test sample loading device according to an embodiment of the present invention; Figure 5 This is a temperature curve of the SiC composite shell using the sample loading device of the present invention under 1600°C and 7H steam oxidation thermal shock. Detailed Implementation

[0018] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] The nuclear fuel cladding simulation test sample loading device of the present invention is used for loading samples for high-temperature steam oxidation thermal shock tests on nuclear fuel cladding, specifically for placing samples of nuclear fuel cladding on it and conducting high-temperature steam oxidation thermal shock tests.

[0020] like Figure 1 , Figure 2 As shown, a nuclear fuel cladding simulation test sample loading device (hereinafter referred to as the sample loading device) according to an embodiment of the present invention includes a support body 10, a support assembly 20, a push rod 30, and a temperature measuring tube 40. The support assembly 20 is connected to one side of the support body 10; the push rod 30 and the temperature measuring tube 40 are respectively inserted into the support body 10 and located on at least one side of the support assembly 20.

[0021] Since the entire sample loading device needs to be used in a high-temperature steam environment, the main support 10, support assembly 20, push rod 30, and temperature measuring tube 40 are all made of high-temperature oxidation-resistant materials, while also possessing characteristics such as high high-temperature strength and low heat capacity, to ensure the service life of the sample loading device in a high-temperature steam environment and to prevent the accuracy of test results from being affected by excessive heat capacity. The aforementioned materials can be at least one of alumina, zirconium oxide, and SiC ceramics.

[0022] Among them, the support body 10 serves as the load-bearing structure of the entire sample loading device, integrating the support component 20, push rod 30, and temperature measuring tube 40 into one unit.

[0023] Combination Figures 1-3 The support body 10 may structurally include a support plate 11 and a connecting rod 12. The support plate 11 has opposing first and second surfaces, the first surface forming a first side of the support body 10 and the second surface forming a second side of the support body 10. The connecting rod 12 is perpendicularly connected to the second surface of the support plate 11.

[0024] The support assembly 20 is perpendicular to and connected to the first surface of the support plate 11, thus being located on the first side of the support body 10. The size of the support plate 11 should be as small as possible while ensuring a stable connection between the support assembly 20, the push rod 30, and the temperature measuring tube 40, so as not to affect the entry and exit of the support body 10 into the furnace chamber of the high-temperature furnace or to avoid affecting the flow of high-temperature steam in the furnace chamber.

[0025] The support disk 11 can be, but is not limited to, a circular disk or a polygonal disk.

[0026] The support plate 11 may also be provided with several connecting holes, which are used for the mating connection of the support component 20, the insertion of the push rod 30, and the insertion of the temperature measuring tube 40, respectively. Specifically, the connecting holes can be divided into a first connecting hole 101, a second connecting hole 102, and a third connecting hole 103. The first connecting hole 101 is used for the mating connection of the support component 20, the second connecting hole 102 is used for the insertion of the push rod 30, and the third connecting hole 103 is used for the insertion of the temperature measuring tube 40. The first connecting hole 101 can be a through hole or a blind hole, and the second connecting hole 102 and the third connecting hole 103 are preferably through holes penetrating both opposite surfaces of the support plate 11.

[0027] When used inside the furnace of a high-temperature furnace, in order to ensure uniform flow of high-temperature steam and avoid obstructing the flow of high-temperature steam, the support body 10 also includes a steam channel 110, which passes through the support plate 11 and the connecting rod 12.

[0028] The connecting rod 12 is connected to the second surface of the support plate 11 with one end facing and perpendicular to it. The connecting rod 12 may be, but is not limited to, a round rod, and preferably the central axis of the connecting rod 12 is in line with the center line of the support plate 11.

[0029] The support component 20 is connected to the first side of the support body 10, and a support position is formed on the support component 20 for placing the shell sample 100.

[0030] Specifically, in Figure 1 and Figure 2 In the illustrated embodiment, the support assembly 20 includes two support rods 21 and a plurality of V-shaped rods 22. The two support rods 21 are arranged parallel to each other and spaced apart, with one end connected to the first side of the support body 10, specifically perpendicular to the support plate 11 and connected to the first surface of the support plate 11, so that the entire support assembly 20 is suspended and connected to one side of the support body 10. The plurality of V-shaped rods 22 are at least two V-shaped rods 22, which are spaced apart along the axial direction of the support rods 21 and connected between the two support rods 21, defining a V-shaped support position between the two support rods 21; the V-shaped support position is a V-shaped groove.

[0031] Corresponding to the two support rods 21, the support plate 11 is provided with two first connecting holes 101 to cooperate with the two support rods 21.

[0032] During sample loading, the shell sample 100 is placed on the V-shaped support position and is stably loaded onto the support position by sinking under the action of gravity, thus achieving stable support for the shell sample 100.

[0033] Preferably, the support rod 21 is a round rod, and the V-shaped rod 22 is formed by the angled connection of two round rods. This makes the contact between the support component 20 and the shell sample 100 a point contact, thereby achieving point support for the shell sample 100, minimizing the contact area between the support component 20 and the shell sample 100, ensuring sufficient contact between the shell sample 100 and the steam, and achieving complete oxidation of the shell sample 100.

[0034] refer to Figure 2 and Figure 4 The push rod 30 is movably mounted on the support body 10, specifically on the support plate 11 of the support body 10. The push rod 30 is axially parallel to the support assembly 20. The push rod 30 has a first end and a second end. The first end of the push rod 30 is located on the first side of the support body 10 and directly opposite the support position, while the second end of the push rod 30 is located on the second side of the support body 10. The push rod 30 can move back and forth axially relative to the support body 10. Adjusting the length of the first end of the push rod 30 on the first side of the support body 10 allows it to push the shell sample 100, causing the shell sample 100 to move on the support assembly 20 and preventing the shell sample 100 from sticking to the support assembly 20.

[0035] Specifically, the push rod 30 may include a rod body 31 and an end plate 32. The rod body 31 is inserted into the support plate 11 of the support body 10 through a second connecting hole 102, and is positioned between the two support rods 21. The end plate 32 is connected to the first end of the rod body 31 and is positioned on the first side of the support body 10. The end plate 32 is used to contact the end face of the casing sample 100, and the end plate 32 can be moved back and forth in the direction of approaching and moving away from the casing sample 100 by pushing and pulling the rod body 31. The axis of the push rod 30 is aligned with the axis of the casing sample 100 as much as possible to minimize damage to the casing sample 100 during pushing.

[0036] The end plate 32 is preferably a circular plate with a diameter greater than or equal to the outer diameter of the casing sample 100, so as to ensure that the plane of the end plate 32 covers the cross-section of the casing sample 100. The end plate 32 is preferably a perforated plate to ensure that water vapor is not blocked from passing through.

[0037] For example Figure 1 and Figure 2 As shown, the temperature measuring tube 40 is inserted into the support body 10 and parallel to the support assembly 20. Specifically, the temperature measuring tube 40 is inserted into the support plate 11 of the support body 10 through a third connecting hole 103, and the temperature measuring tube 40 is located on one side of the support assembly 20. The temperature measuring tube 40 is used for the thermocouple 50 to be inserted therein to measure the temperature of the encapsulated sample 100.

[0038] Taking the support component 20 with its support position facing upwards as an example, the temperature measuring tube 40 is located below the support component 20 so that it will not affect the quenching thermal shock operation performed on the cladding sample 100 after oxidation.

[0039] In some embodiments, the nuclear fuel cladding simulation test sample loading device further includes a thermocouple 50, which is inserted into a temperature measuring tube 40. The temperature measuring end of the thermocouple 50 is close to or in contact with the outer surface of the cladding sample 100 to measure the temperature of the cladding sample 100. The connecting end of the thermocouple 50 extends out of the temperature measuring tube 40 for connection to a control terminal or monitoring device.

[0040] To meet the requirements for temperature measurement in a high-temperature environment of 1600℃, the preferred thermocouple 50 is a platinum-rhodium thermocouple.

[0041] The method of using the nuclear fuel cladding simulation test sample loading device of the present invention, namely, for realizing a high-temperature steam oxidation thermal shock test of nuclear fuel cladding, is described in reference. Figures 1-4 The method of use may include the following steps: S1. Place the cladding sample 100 to be tested on the support assembly 20 of the nuclear fuel cladding simulation test sample loading device. The temperature measuring end of the thermocouple 50 is close to or in contact with the outer surface of the cladding sample 100, so that the first end of the push rod 30 of the nuclear fuel cladding simulation test sample loading device is close to the support body 10 and away from the cladding sample 100.

[0042] The action of bringing the first end of the push rod 30 closer to the support body 10 and away from the casing sample 100 can be performed before or after the casing sample 100 is placed. The distance between the push rod 30 and the casing sample 100 is greatest when the end plate 32 of the push rod 30 abuts against the first surface of the support plate 11 of the support body 10.

[0043] S2. The nuclear fuel cladding simulation test loading device with cladding sample 100 is pushed into the furnace of the high-temperature furnace to perform high-temperature steam oxidation on the cladding sample 100.

[0044] Before step S2, the high-temperature furnace is heated to a set temperature, such as 1600°C, and steam is introduced into the furnace chamber (also known as the reaction chamber). After the temperature and steam flow rate in the furnace chamber are stable, the coated sample 100 is sent into the reaction chamber for high-temperature steam oxidation using a sample loading device. The oxidation time is 7 hours.

[0045] S3. After completing the high-temperature steam oxidation, remove the nuclear fuel cladding simulation test loading device with cladding sample 100 from the high-temperature furnace and place it above the quenching water pool. Turn the nuclear fuel cladding simulation test loading device over so that the cladding sample 100 falls into the quenching water pool to complete the quenching thermal shock action.

[0046] After the high-temperature steam oxidation is completed, the process also includes: pushing the push rod 30 to push the shell sample 100, so that the shell sample 100 moves 1mm to 2mm on the support component 20 to prevent the shell sample 100 from sticking to the support component 20, so as to ensure the successful completion of the quenching thermal shock action.

[0047] After the cladding sample 100 is removed from the reaction chamber and stopped above the quenching water pool using the nuclear fuel cladding simulation test sample loading device, the entire sample loading device is rotated 180° (with the V-shaped support opening facing down) and the cladding sample 100 falls into the quenching water pool (i.e., the cooling water pool) to complete the quenching thermal shock action.

[0048] After the cladding sample 100 has cooled, it is retrieved from the quenching water tank to complete the test.

[0049] In one application embodiment of the present invention, a quenching thermal shock test was successfully completed on a SiC composite cladding after oxidation for 7 hours in a high-temperature steam environment at 1600℃. The test was successful on the first attempt, indicating that the sample loading device and test procedure are reliable. The temperature curve of the SiC composite cladding under 1600℃ and 7H steam oxidation thermal shock is shown below. Figure 5 As shown.

[0050] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A sample loading device for a nuclear fuel cladding simulation test, characterized in that, The sample loading device for high-temperature steam oxidation thermal shock tests of nuclear fuel cladding includes a support body, support components, push rods, and temperature measuring tubes. The support assembly is connected to the first side of the support body, and a support position is formed on the support assembly. The support position is used to support the shell sample through point contact. The support assembly includes two support rods and a plurality of V-shaped rods. The two support rods are connected to the first side of the support body in parallel and spaced apart. The plurality of V-shaped rods are spaced apart along the axial direction of the support rods and connected between the two support rods, defining a V-shaped support position between the two support rods. The push rod passes through the support body and is parallel to the support assembly; the first end of the push rod is located on the first side of the support body and is directly opposite the support position, and the opposite second end of the push rod is located on the second side of the support body; the push rod is axially movable relative to the support body to push the shelled sample; the push rod includes a rod body and an end plate, the rod body passes through the support body, and the end plate is connected to the first end of the rod body and is used to contact the end face of the shelled sample; The temperature measuring tube is inserted through the support body and parallel to the support assembly. The temperature measuring tube is used for thermocouples to be inserted therethrough to measure the temperature of the encapsulated sample.

2. The nuclear fuel cladding simulation test sample loading device according to claim 1, characterized in that, The support body includes a support plate and a connecting rod; the support plate has a first surface and a second surface opposite to each other, the first surface of the support plate forms a first side of the support body, and the connecting rod is perpendicularly connected to the second surface of the support plate.

3. The nuclear fuel cladding simulation test sample loading device according to claim 2, characterized in that, The support body also includes a steam channel that extends through the support plate and the connecting rod.

4. The nuclear fuel cladding simulation test sample loading device according to claim 1, characterized in that, The end plate is a circular plate with a diameter greater than or equal to the outer diameter of the shell sample; and / or, the end plate is a perforated plate.

5. The nuclear fuel cladding simulation test sample loading device according to any one of claims 1-4, characterized in that, The support body, support components, push rod, and temperature measuring tube are all made of high-temperature oxidation resistant materials.

6. The nuclear fuel cladding simulation test sample loading apparatus according to any one of claims 1-4, characterized in that, The nuclear fuel cladding simulation test sample loading device also includes a thermocouple, which is inserted into the temperature measuring tube, with the temperature measuring end of the thermocouple close to or in contact with the outer surface of the cladding sample.

7. A method of using the nuclear fuel cladding simulation test sample loading device according to any one of claims 1-6, characterized in that, The method of using nuclear fuel cladding for high-temperature steam oxidation thermal shock testing includes the following steps: S1. Place the cladding sample to be tested on the support assembly of the nuclear fuel cladding simulation test sample loading device, with the thermocouple's measuring end close to or against the outer surface of the cladding sample, so that the first end of the push rod of the nuclear fuel cladding simulation test sample loading device is close to the support body and away from the cladding sample. S2. The nuclear fuel cladding simulation test loading device with the cladding sample is pushed into the furnace of the high-temperature furnace to perform high-temperature steam oxidation on the cladding sample. S3. After completing the high-temperature steam oxidation, remove the nuclear fuel cladding simulation test sample loading device with the cladding sample from the high-temperature furnace and place it above the quenching water pool. Turn the nuclear fuel cladding simulation test sample loading device over so that the cladding sample falls into the quenching water pool to complete the quenching thermal shock action.

8. The method of using the nuclear fuel cladding simulation test sample loading device according to claim 7, characterized in that, After high-temperature steam oxidation is completed, the push rod is pushed to move the shell sample 1mm to 2mm on the support assembly, preventing the shell sample from sticking to the support assembly.

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