Method and system for measuring thickness of irradiated fuel core and method and system for measuring heat conductivity of irradiated fuel core

Abstract

The invention discloses a thickness measurement method, a thermal conductivity measurement method and a thermal conductivity measurement system for a fuel core after irradiation. The thickness measurement method comprises the following steps: carrying out levelness correction on a laser thickness measurement platform by adopting a standard thickness gauge block which is verified to be qualified; after correction is completed, the height of the laser thickness measuring platform without the thermal conductivity sample is measured; a thermal conductivity sample is placed on the laser thickness measuring platform, the height of the laser thickness measuring platform where the thermal conductivity sample is placed is obtained through measurement, and measurement is conducted multiple times; and obtaining a height measurement average value according to multiple measurements, and subtracting the height measurement value without the thermal conductivity sample from the height measurement average value to obtain a thickness measurement value of the thermal conductivity sample. The laser thickness measurement mode in the hot chamber is adopted, the operation requirement of the irradiated heat conductivity sample in the hot chamber is met, and the adverse effect of the high-radioactivity sample on personnel is greatly reduced; and meanwhile, the thickness measurement precision of the irradiated thermal conductivity sample is ensured.

Description

Technical Field

[0001] The present application belongs to the technical field of irradiated fuel material performance measurement, and specifically relates to a method for measuring the thickness of a fuel core after irradiation, and a method and system for measuring thermal conductivity. Background Art

[0002] During the service of fuel assemblies, the heat generated during irradiation needs to be continuously removed from the fuel assemblies through cooling water. Therefore, the change in the thermal conductivity of the fuel core during the irradiation process will inevitably affect the heat removal inside the fuel core. The physical quantity that measures the thermal conductivity of the fuel is thermal conductivity. Understanding the change law of the thermal conductivity of the fuel core in the reactor is of great significance to the use of fuel assemblies and the safe operation of the reactor.

[0003] During the irradiation process of the fuel assembly in the reactor, the nuclear fuel will experience reconstruction phenomena such as grain refinement, fission gas redistribution, and defect generation, all of which will lead to a decrease in the thermal conductivity of the fuel. As the burnup increases, the thermal conductivity of the fuel core decreases, the heat transfer performance of the fuel core will deteriorate, and the overall temperature increase of the fuel element will lead to abnormal swelling and mechanical instability of the fuel assembly, affecting the safe operation of the reactor. Therefore, conducting research on the measurement of thermal conductivity of irradiated nuclear fuel has important scientific and theoretical value and engineering value.

[0004] The thermal conductivity test method of the fuel core after irradiation is usually the laser flash method. Its principle is that under a certain set temperature T (constant temperature condition), a laser source emits a beam of light pulses at an instant, and evenly irradiates the lower surface of the sample, so that the lower surface absorbs light energy and the temperature rises instantly, and as the hot end, it transmits energy to the cold end (upper surface) in a one-dimensional heat conduction manner. Use an infrared detector to continuously measure the corresponding temperature rise process at the center of the upper surface, and obtain the relationship curve between the temperature (detector signal) increase and time, and then obtain the thermal diffusion coefficient α of the material at temperature T through the following equation.

[0005]

[0006] Where, d is the thickness of the sample, accurate to 0.01 mm; t 50 is the half heating time, also known as t 1 / 2 , is the time required for the surface temperature (detector signal) of the sample to rise to half of the maximum value after receiving the light pulse irradiation.

[0007] Then, the thermal conductivity at that temperature can be calculated based on the thermal diffusion coefficient, specific heat capacity and density at a known temperature.

[0008] From the above, it can be seen that the accuracy of the sample thickness is closely related to the thermal conductivity measurement results of the sample. The radioactivity of the irradiated fuel core is very strong. The commonly used non-radioactive samples can be measured with a contact micrometer screw ruler with an accuracy better than 10μm. However, during the measurement process, personnel need to contact the measured object, and the operation process is complicated, which cannot meet the requirements of the hot chamber operation of the thermal conductivity sample of the irradiated fuel core. Summary of the invention

[0009] In order to achieve the accuracy and safety of the thickness measurement of the thermal conductivity sample of the fuel core after irradiation, the present application proposes a method for measuring the thickness of the fuel core after irradiation, a thermal conductivity measurement method and a system. The present application adopts a non-contact measurement method to achieve the measurement requirements of the thermal conductivity sample of the fuel core after irradiation in the hot chamber, while ensuring that the measurement accuracy meets the experimental requirements of the thermal conductivity measurement of the fuel core after irradiation.

[0010] This application is implemented through the following technical solutions:

[0011] A method for measuring the thickness of a fuel core after irradiation, the thickness measuring method comprising:

[0012] Use qualified standard thickness gauge blocks to calibrate the levelness of the laser thickness measuring platform;

[0013] After the calibration is completed, the height of the laser thickness measurement platform without the thermal conductivity sample is measured;

[0014] Placing the thermal conductivity sample on the laser thickness measuring platform, measuring the height of the laser thickness measuring platform on which the thermal conductivity sample is placed, and repeating the measurement multiple times for each thermal conductivity sample;

[0015] The height of the laser thickness measuring platform on which the thermal conductivity sample is placed is obtained according to multiple measurements to obtain an average height measurement value, and the height measurement value without the thermal conductivity sample placed is subtracted from the average height measurement value to obtain a thickness measurement value of the thermal conductivity sample.

[0016] In some embodiments, the horizontal calibration of the laser thickness measuring platform using a qualified standard thickness gauge block specifically includes:

[0017] Measure the height of the laser thickness measuring platform without placing the standard thickness gauge block;

[0018] The qualified standard thickness gauge block is placed on the laser thickness measuring platform, and the height of the laser thickness measuring platform on which the standard thickness gauge block is placed is measured. The average value is calculated multiple times as the height measurement result of the standard thickness gauge block;

[0019] Subtract the height measurement result of the standard thickness gauge block from the height measurement result of the standard thickness gauge block not being placed, to obtain the thickness measurement result of the standard thickness gauge block;

[0020] The thickness measurement result of the standard thickness gauge block is compared with the calibration result of the standard thickness gauge block. If the difference between the two does not meet the experimental accuracy requirement, the laser thickness measurement platform is adjusted and returned for the next calibration until the measurement result meets the experimental accuracy requirement.

[0021] In some embodiments, the thickness measurement method further comprises:

[0022] The thickness measurement process of the thermal conductivity sample of the fuel core after irradiation is completed by manipulating the relevant equipment in the hot chamber through the manipulator.

[0023] In a second aspect, the present application proposes a method for measuring the thermal conductivity of a fuel core after irradiation, the thermal conductivity measurement method comprising:

[0024] Measure the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation. If the measured radiation level does not exceed the threshold, continue the subsequent thermal conductivity measurement process, otherwise exit;

[0025] The thermal conductivity sample is transported to a thermal conductivity measurement hot chamber, and the thickness of the thermal conductivity sample is measured by the above-mentioned thickness measurement method;

[0026] Determine whether the reflective condition of the surface of the thermal conductivity sample after the thickness measurement is completed meets the requirements. If the reflective condition does not meet the requirements, process the surface of the thermal conductivity sample so that its surface light energy absorption ratio meets the requirements before transferring the thermal conductivity sample to the thermal conductivity measuring device. Otherwise, directly transfer the thermal conductivity sample to the thermal conductivity measuring device.

[0027] According to the measured thickness of the thermal conductivity sample, a thermal conductivity measurement test is performed on the thermal conductivity measuring device to obtain the thermal diffusion coefficient of the thermal conductivity sample;

[0028] The thermal conductivity of the irradiated fuel core is calculated based on the thermal diffusivity of the thermal conductivity sample.

[0029] In some embodiments, the surface of the thermal conductivity sample is processed, specifically comprising:

[0030] A layer of graphite powder or other high emissivity coating is sprayed on the surface of the thermal conductivity sample.

[0031] In some embodiments, the thermal conductivity calculation formula is:

[0032] λ(T)=α(T)*C p(T)*ρ(T)

[0033] Where λ(T) is the thermal conductivity at temperature T, α(T) is the thermal diffusivity at temperature T, C p (T) is the specific heat at temperature T, and ρ(T) is the density at temperature T.

[0034] In some embodiments, before the step of measuring the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation, the method further includes:

[0035] Thermal conductivity sample preparation of fuel core;

[0036] After sample preparation, irradiation experiments were performed;

[0037] After the irradiation experiment is completed, the irradiated thermal conductivity sample is obtained.

[0038] In a third aspect, the present application proposes a system for measuring the thickness of a fuel core after irradiation, the thickness measurement system comprising:

[0039] A correction module, wherein the correction module is configured to: use a qualified standard thickness gauge block to perform horizontal correction on the laser thickness measurement platform;

[0040] A measuring module A, wherein the measuring module A is configured to: after calibration is completed, measure the height of the laser measuring platform without placing the thermal conductivity sample;

[0041] A measuring module B, wherein the measuring module B is configured to: place the thermal conductivity sample on the laser thickness measuring platform, measure the height of the laser thickness measuring platform on which the thermal conductivity sample is placed, and repeat the measurement multiple times for each sample;

[0042] And, a calculation module A, wherein the calculation module A is configured to: obtain an average height measurement value based on the height of the laser thickness measuring platform on which the thermal conductivity sample is placed obtained by multiple measurements, and subtract the height measurement value without the thermal conductivity sample from the average height measurement value to obtain the thickness measurement value of the thermal conductivity sample.

[0043] In a fourth aspect, the present application proposes a system for measuring thermal conductivity of a fuel core after irradiation, the thermal conductivity measurement system comprising:

[0044] A radiation determination module, wherein the radiation determination module is configured to: measure the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation, and if the radiation level does not exceed a threshold, drive the thickness measurement module to perform thickness measurement;

[0045] A thickness measurement module, wherein the thickness measurement module is configured to: transport the thermal conductivity sample to a thermal conductivity measurement chamber and measure the thickness using the above-mentioned thickness measurement method;

[0046] A state determination module, wherein the state determination module is configured to: determine whether the reflective condition of the surface of the thermal conductivity sample after the thickness measurement is completed meets the requirements; if the reflective condition does not meet the requirements, the surface of the thermal conductivity sample is processed to make its surface light energy absorption ratio meet the requirements, and then the irradiated thermal conductivity sample is transferred to the thermal conductivity measurement device; otherwise, the thermal conductivity sample is directly transferred to the thermal conductivity measurement device;

[0047] A thermal diffusion coefficient measurement module, wherein the thermal diffusion coefficient measurement module is configured to: perform a thermal conductivity measurement test according to the measured thickness of the thermal conductivity sample to obtain the thermal diffusion coefficient of the thermal conductivity sample;

[0048] And, a calculation module B, wherein the calculation module B is configured to calculate the thermal conductivity of the fuel core after irradiation according to the thermal diffusion coefficient of the thermal conductivity sample.

[0049] In some embodiments, the thermal conductivity measurement system further comprises:

[0050] A sample preparation module, wherein the sample preparation module is configured to: prepare a thermal conductivity sample of a fuel core;

[0051] An irradiation module, wherein the irradiation module is configured to: implement an irradiation experiment of the thermal conductivity sample;

[0052] A disassembly module, wherein the disassembly module is configured to: take out the irradiated thermal conductivity sample from the irradiation device and transport it to a sample preparation hot chamber;

[0053] A cleaning and drying module is configured to: clean and dry the irradiated thermal conductivity sample in the sample preparation chamber.

[0054] The present application proposes a method for measuring the thickness of a fuel core after irradiation, a method for measuring thermal conductivity and a system thereof. For highly radioactive samples after irradiation, a laser thickness measurement method is used in a hot chamber, thereby achieving the hot chamber operation requirements for the thermal conductivity samples after irradiation, and greatly reducing the adverse effects of highly radioactive samples on personnel. At the same time, before the actual measurement, the laser thickness measurement platform is checked using a qualified standard thickness brightness to ensure that its measurement accuracy meets the experimental requirements, thereby ensuring the thickness measurement accuracy of the thermal conductivity samples after irradiation.

[0055] The present application proposes a method for measuring the thickness of a fuel core after irradiation, a method for measuring thermal conductivity, and a system for measuring the thickness of a thermal conductivity sample of a fuel core after irradiation. The accuracy of the operation in the hot chamber and the measurement results can meet the experimental requirements for measuring the thermal conductivity of the fuel core sample, thereby providing data support for the measurement of the thermal conductivity of the fuel core and realizing the measurement of the thermal conductivity of the fuel core after irradiation.

[0056] The present application proposes a method for measuring the thickness of a fuel core after irradiation, a method for measuring the thermal conductivity and a system thereof, which realize the measurement of the thermal conductivity of the fuel core after irradiation, thereby further obtaining the variation law of the thermal conductivity of the fuel core before and after irradiation, and providing a technical reference for the improvement and development of new fuel cores. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide a further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0058] Figure 1 This is a flow chart of the thickness measurement method according to an embodiment of the present application;

[0059] Figure 2 This is a flow chart of the thermal conductivity measurement method of an embodiment of the present application;

[0060] Figure 3 This is a principle block diagram of a thickness measurement system according to an embodiment of the present application;

[0061] Figure 4 This is a principle block diagram of the thermal conductivity measurement system according to an embodiment of the present application. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0063] Example:

[0064] In order to achieve the operation requirements of the thermal conductivity sample of the irradiated fuel core in the hot chamber and ensure that the thickness measurement accuracy can meet the requirements of the thermal conductivity measurement experiment of the irradiated fuel core, this embodiment proposes a method for measuring the thickness of the irradiated fuel core. The method uses a manipulator to achieve operation in the hot chamber, assists in completing the thickness measurement of the irradiated fuel core, and uses non-destructive measurement technology to achieve high-precision measurement to meet the requirements of the thermal conductivity measurement experiment of the irradiated fuel core.

[0065] like Figure 1 As shown, the thickness measurement method proposed in this embodiment specifically includes the following steps:

[0066] Step 100, using a qualified standard thickness gauge block to calibrate the levelness of the laser thickness measuring platform.

[0067] This step first uses a qualified standard thickness gauge block to calibrate the horizontality of the laser thickness measurement platform to ensure the accuracy of subsequent thickness measurements. The specific calibration process is as follows:

[0068] Step 101, measuring the height of the laser thickness measuring platform without placing a standard thickness gauge block.

[0069] Step 102, placing a qualified standard thickness gauge block on a laser thickness measuring platform, measuring the height of the laser thickness measuring platform on which the standard thickness gauge block is placed, measuring multiple times (at least three times) and calculating the average value as the height measurement result of the standard thickness gauge block.

[0070] Step 103, subtract the height measurement result of the gauge block without the standard thickness gauge block from the height measurement result of the gauge block with the standard thickness gauge block placed, to obtain the thickness measurement result of the gauge block.

[0071] Step 104, compare the thickness measurement result of the gauge block with the calibration result of the gauge block. If the difference between the two does not meet the experimental accuracy requirement, adjust the laser thickness measurement platform and return to step 101 for the next calibration until the measurement result meets the experimental accuracy requirement.

[0072] Step 200, after the calibration is completed, the height of the laser thickness measurement platform without the thermal conductivity sample placed thereon is measured.

[0073] Step 300, placing a thermal conductivity sample on a laser thickness measurement platform, measuring the height of the laser thickness measurement platform on which the thermal conductivity sample is placed, and repeating the measurement multiple times (at least three times) for each sample.

[0074] Step 400, obtaining an average height measurement value based on the height of the laser thickness measuring platform on which the thermal conductivity sample is placed obtained by multiple measurements, and subtracting the height measurement value without the thermal conductivity sample from the average height measurement value to obtain the thickness measurement value of the thermal conductivity sample.

[0075] The thickness measurement method proposed in this embodiment uses a qualified standard thickness block to check the platform before actual measurement. After the inspection meets the experimental requirements, the thermal conductivity sample can be placed for thickness measurement. The single sample is measured repeatedly at least three times and the average value is taken. The average value is the thickness measurement result of the thermal conductivity sample of the fuel core, thereby realizing accurate measurement of the thickness of the thermal conductivity sample of the fuel core after irradiation.

[0076] During the thickness measurement of the thermal conductivity sample of the fuel core, operators outside the hot chamber can use a manipulator to manipulate the relevant equipment in the hot chamber to complete the thickness measurement process of the thermal conductivity sample of the irradiated fuel core, which greatly reduces the adverse effects of highly radioactive samples on personnel.

[0077] The thickness measurement method proposed in this embodiment can realize the thickness measurement of the thermal conductivity sample of the fuel core after irradiation. The accuracy of the operation in the hot chamber and the measurement results can meet the experimental requirements of the thermal conductivity measurement of the fuel core sample, thereby providing data support for the thermal conductivity measurement of the fuel core.

[0078] Based on the same technical concept as above, this embodiment also proposes a method for measuring the thermal conductivity of the fuel core after irradiation, such as Figure 2 As shown, the thermal conductivity measurement method proposed in this embodiment specifically includes the following steps:

[0079] Step S1, measuring the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation. If the radiation level does not exceed the threshold, the subsequent thermal conductivity measurement process continues, otherwise exits. In order to prevent the gamma rays emitted by the sample from damaging the thermal conductivity measurement equipment in the hot chamber, it is necessary to monitor the radiation level of the surface of the thermal conductivity sample after irradiation. If the radiation level is too high, the thermal conductivity measurement process cannot be performed. If the radiation level meets the requirements, the thermal conductivity measurement process continues.

[0080] Optionally, before step S1, the following steps are also included: thermal conductivity sample preparation, irradiation and disassembly and cutting. The thermal conductivity sample is prepared before irradiation, and the size of the prepared thermal conductivity sample can preferably be 12.7 mm in diameter and 2 mm in thickness. The surface should be flat and the parallel error should be within 0.5% of the thickness. No surface defects (such as sand holes, scratches, stripes, etc.) are allowed, because these defects will seriously affect the experimental results.

[0081] The prepared thermal conductivity samples are placed in the corresponding irradiation devices. In order to ensure the surface state of the thermal conductivity samples after irradiation, special irradiation devices are customized for the thermal conductivity samples. That is, the size structure of the irradiation container matches the size structure of the thermal conductivity samples. At the same time, these irradiation devices must be easy to disassemble and sample in the hot chamber.

[0082] The irradiation device with the thermal conductivity sample is placed in the reactor for irradiation. After irradiation to the target fuel consumption, the irradiation device is taken out and transferred to the dismantling and cutting hot chamber. In the dismantling and cutting hot chamber, the thermal conductivity sample is taken out from the irradiation device and transferred to the sample preparation hot chamber for cleaning (using alcohol or acetone, etc.) and drying.

[0083] Step S2, transporting the thermal conductivity sample to a thermal conductivity measurement hot chamber, and measuring the thickness of the thermal conductivity sample after irradiation using the above thickness measurement method.

[0084] Step S3, judge whether the reflection of the surface of the irradiated thermal conductivity sample after the thickness measurement meets the requirements. If the reflection of the sample is serious (i.e., it does not meet the requirements), the surface of the thermal conductivity sample needs to be processed to make its surface light energy absorption ratio meet the requirements, and then the irradiated thermal conductivity sample is transferred to the thermal conductivity measurement device, otherwise the irradiated thermal conductivity sample is directly transferred to the thermal conductivity measurement device. If the sample is seriously reflective, that is, the surface light energy absorption ratio of the sample is less than the threshold, the accuracy and reliability of the subsequent thermal conductivity measurement sample results will be reduced. Therefore, this step S3 needs to process the surface of the thermal conductivity sample according to the reflection of the surface of the thermal conductivity sample to ensure the measurement accuracy. Specifically, a layer of graphite powder or other high-emissivity coating can be sprayed on the surface of the sample with the help of a manipulator to clamp the graphite can to ensure that the surface light energy absorption ratio of the sample meets the requirements.

[0085] Step S4, based on the measured thickness of the thermal conductivity sample, a thermal conductivity measurement test is performed on the thermal conductivity measurement device to obtain the thermal diffusivity of the thermal conductivity sample. In step S4, a manipulator can be used to place the thermal conductivity sample on a sample holder of the thermal conductivity measurement device, and the heating furnace is lowered to start the thermal conductivity measurement test. During the test, the temperature stability should be manually or automatically checked, and the configured safety monitoring device is used to monitor the working state of the thermal conductivity measurement device in the hot chamber.

[0086] Step S5, according to the thermal diffusivity of the thermal conductivity sample, the thermal conductivity of the fuel core after irradiation is calculated. In step S5, the thermal conductivity of the fuel core after irradiation is calculated by the relationship between the thermal conductivity (thermal conductivity) and the thermal diffusivity, that is, the following formula:

[0087] λ(T)=α(T)*C p (T)*ρ(T)

[0088] Where λ(T) is the thermal conductivity at temperature T, α(T) is the thermal diffusivity at temperature T, C p (T) is the specific heat at temperature T, and ρ(T) is the density at temperature T. It can be seen from the above formula that the thermal conductivity at temperature T can be calculated when the thermal diffusion coefficient, specific heat and density at temperature T are known. Among them, the thermal conductivity can be measured using the above-mentioned thermal conductivity measuring device, and the density uses the apparent density (also known as bulk density, i.e. mass / apparent volume), which is generally tested at room temperature. Its change with temperature can be corrected using the thermal expansion coefficient table of the material. When the measurement temperature is not too high and the density change is not too large, it can be approximately considered to be unchanged. The specific heat can be measured using an empirical value or using differential scanning calorimetry (DSC).

[0089] The thermal conductivity measurement method proposed in this embodiment can realize the thermal conductivity measurement of the fuel core sample after irradiation, so as to further obtain the change law of the thermal conductivity of the fuel core before and after irradiation, and provide technical support and technical reference for the improvement and development of new fuel cores.

[0090] During the thermal conductivity measurement process of the thermal conductivity measurement method proposed in this embodiment, operators outside the hot chamber can use a manipulator to manipulate relevant equipment in the hot chamber to complete the preparation, transportation and thermal conductivity measurement of the thermal conductivity sample after irradiation, which greatly reduces the adverse effects of highly radioactive samples on personnel.

[0091] Based on the same technical concept as above, this embodiment also proposes a system for measuring the thickness of a fuel core after irradiation, such as Figure 3 As shown, the thickness measurement system proposed in this embodiment specifically includes:

[0092] The correction module is configured to: use a qualified standard thickness gauge block to perform horizontal correction on the laser thickness measurement platform.

[0093] The measuring module A is configured to measure the height of the laser measuring platform without placing the thermal conductivity sample after the calibration is completed.

[0094] Measuring module B, the measuring module B is configured to: place the thermal conductivity sample on the laser thickness measuring platform, measure the height of the thermal conductivity sample, and repeat the measurement multiple times for each sample.

[0095] And, a calculation module A, which is configured to: obtain an average height measurement value based on the heights of the thermal conductivity samples placed obtained by multiple measurements, and subtract the height measurement value without placing the thermal conductivity sample from the average height measurement value to obtain the thickness measurement value of the thermal conductivity sample.

[0096] It should be noted that the specific implementation process of each functional module in the above thickness measurement system is as described in the above steps 100 to 400, and will not be repeated here.

[0097] This embodiment also proposes a system for measuring the thermal conductivity of a fuel core after irradiation. Figure 4 As shown, the thermal conductivity measurement system proposed in this embodiment specifically includes:

[0098] The radiation determination module is configured to: measure the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation, and if the radiation level does not exceed a threshold, drive the thickness measurement module to perform thickness measurement.

[0099] The thickness measurement module is configured to: transport the thermal conductivity sample to a thermal conductivity measurement hot chamber, and use the above thickness measurement method to measure the thickness of the thermal conductivity sample after irradiation.

[0100] A state determination module is configured to determine whether the reflective condition of the surface of the irradiated thermal conductivity sample after the thickness measurement meets the requirements. If the reflective condition of the sample is serious (i.e., it does not meet the requirements), the surface of the thermal conductivity sample needs to be processed so that its surface light energy absorption ratio meets the requirements, and then the irradiated thermal conductivity sample is transferred to the thermal conductivity measuring device. Otherwise, the thermal conductivity sample is directly transferred to the thermal conductivity measuring device.

[0101] The thermal diffusion coefficient measurement module is configured to: perform a thermal conductivity measurement test according to the measured thickness of the thermal conductivity sample to obtain the thermal diffusion coefficient of the thermal conductivity sample.

[0102] And, a calculation module B, wherein the calculation module B is configured to calculate the thermal conductivity of the fuel core after irradiation according to the thermal diffusion coefficient of the thermal conductivity sample.

[0103] It should be noted that the specific implementation process of each functional module of the thermal conductivity measurement system is as described in the above steps S1-S5, which will not be described in detail here.

[0104] In an optional embodiment, the thermal conductivity measurement system further includes:

[0105] The sample preparation module is configured to prepare the thermal conductivity sample of the fuel core, wherein the size of the prepared thermal conductivity sample may preferably be 12.7 mm in diameter and 2 mm in thickness. The surface should be flat and the parallel error should be within 0.5% of the thickness. No surface defects (such as sand holes, scratches, stripes, etc.) are allowed, as these defects will seriously affect the experimental results.

[0106] In an optional embodiment, the thermal conductivity measurement system further includes:

[0107] Irradiation module, the irradiation module is configured as follows: put the prepared thermal conductivity sample into the corresponding irradiation device. In order to ensure the surface state of the thermal conductivity sample after irradiation, a special irradiation device is customized for the thermal conductivity sample, that is, the size structure of the irradiation container matches the size structure of the thermal conductivity sample, and these irradiation devices must also be convenient for disassembly and sampling in the hot chamber. Put the irradiation device with the thermal conductivity sample into the reactor for irradiation, take out the irradiation device after irradiation to the target burnup, and transport it to the disassembly and cutting hot chamber.

[0108] In an optional embodiment, the thermal conductivity measurement system further includes:

[0109] The disassembly module is configured to: in the disassembly and cutting hot chamber, take out the thermal conductivity sample from the irradiation device and transport it to the sample preparation hot chamber.

[0110] In an optional embodiment, the thermal conductivity measurement system further includes:

[0111] The cleaning and drying module is configured to: clean (using alcohol or acetone, etc.) and dry the irradiated thermal conductivity sample in the sample preparation hot chamber.

[0112] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0113] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0114] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0115] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0116] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for measuring the thickness of a fuel core after irradiation, characterized in that: The thickness measurement method comprises: Use qualified standard thickness gauge blocks to calibrate the levelness of the laser thickness measuring platform; After the calibration is completed, the height of the laser thickness measurement platform without the thermal conductivity sample is measured; Placing the thermal conductivity sample on the laser thickness measuring platform, measuring the height of the laser thickness measuring platform on which the thermal conductivity sample is placed, and repeating the measurement multiple times for each thermal conductivity sample; The height of the laser thickness measuring platform on which the thermal conductivity sample is placed is obtained according to multiple measurements to obtain an average height measurement value, and the height measurement value without the thermal conductivity sample placed is subtracted from the average height measurement value to obtain a thickness measurement value of the thermal conductivity sample.

2. The method for measuring the thickness of a fuel core after irradiation according to claim 1, characterized in that: The horizontal calibration of the laser thickness measuring platform using a qualified standard thickness gauge block specifically includes: Measure the height of the laser thickness measuring platform without placing the standard thickness gauge block; The qualified standard thickness gauge block is placed on the laser thickness measuring platform, and the height of the laser thickness measuring platform on which the standard thickness gauge block is placed is measured. The average value is calculated multiple times as the height measurement result of the standard thickness gauge block; Subtract the height measurement result of the standard thickness gauge block from the height measurement result of the standard thickness gauge block not being placed, to obtain the thickness measurement result of the standard thickness gauge block; The thickness measurement result of the standard thickness gauge block is compared with the calibration result of the standard thickness gauge block. If the difference between the two does not meet the experimental accuracy requirement, the laser thickness measurement platform is adjusted and returned for the next calibration until the measurement result meets the experimental accuracy requirement.

3. A method for measuring thickness of a fuel core after irradiation according to claim 1 or 2, characterized in that: The thickness measurement method further comprises: The thickness measurement process of the thermal conductivity sample of the fuel core after irradiation is completed by manipulating the relevant equipment in the hot chamber through the manipulator.

4. A method for measuring thermal conductivity of a fuel core after irradiation, characterized in that: The thermal conductivity measurement method comprises: Measure the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation. If the measured radiation level does not exceed the threshold, continue the subsequent thermal conductivity measurement process, otherwise exit; The thermal conductivity sample is transported to a thermal conductivity measurement hot chamber, and the thickness of the thermal conductivity sample is measured by the thickness measurement method according to any one of claims 1 to 3; Determine whether the reflective condition of the surface of the thermal conductivity sample after the thickness measurement is completed meets the requirements. If the reflective condition does not meet the requirements, process the surface of the thermal conductivity sample so that its surface light energy absorption ratio meets the requirements before transferring the thermal conductivity sample to the thermal conductivity measuring device. Otherwise, directly transfer the thermal conductivity sample to the thermal conductivity measuring device. According to the measured thickness of the thermal conductivity sample, a thermal conductivity measurement test is performed on the thermal conductivity measuring device to obtain the thermal diffusion coefficient of the thermal conductivity sample; The thermal conductivity of the irradiated fuel core is calculated based on the thermal diffusivity of the thermal conductivity sample.

5. A method for measuring thermal conductivity of a fuel core after irradiation according to claim 4, characterized in that: The processing of the surface of the thermal conductivity sample specifically includes: A layer of graphite powder or other high emissivity coating is sprayed on the surface of the thermal conductivity sample.

6. A method for measuring thermal conductivity of a fuel core after irradiation according to claim 4, characterized in that: The thermal conductivity calculation formula is: λ(T)=α(T)*C p (T)*ρ(T) Where λ(T) is the thermal conductivity at temperature T, α(T) is the thermal diffusivity at temperature T, C p (T) is the specific heat at temperature T, and ρ(T) is the density at temperature T.

7. A method for measuring thermal conductivity of a fuel core after irradiation according to any one of claims 4 to 6, characterized in that: Before the step of measuring the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation, the method further includes: Thermal conductivity sample preparation of fuel core; After the sample preparation, the irradiation experiment was carried out; After the irradiation experiment is completed, the irradiated thermal conductivity sample is obtained.

8. A system for measuring the thickness of a fuel core after irradiation, characterized in that: The thickness measurement system comprises: A correction module, wherein the correction module is configured to: use a qualified standard thickness gauge block to perform horizontal correction on the laser thickness measurement platform; A measuring module A, wherein the measuring module A is configured to: after calibration is completed, measure the height of the laser measuring platform without placing the thermal conductivity sample; A measuring module B, wherein the measuring module B is configured to: place the thermal conductivity sample on the laser thickness measuring platform, measure the height at which the thermal conductivity sample is placed, and repeat the measurement multiple times for each sample; And, a calculation module A, wherein the calculation module A is configured to: obtain an average height measurement value based on multiple measurements of the height of the thermal conductivity sample, and subtract the height measurement value without placing the thermal conductivity sample from the average height measurement value to obtain a thickness measurement value of the thermal conductivity sample.

9. A system for measuring thermal conductivity of fuel core after irradiation, characterized in that: The thermal conductivity measurement system comprises: A radiation determination module, wherein the radiation determination module is configured to: measure the zero-distance radiation level of the surface of the thermal conductivity sample after irradiation, and if the radiation level does not exceed a threshold, drive the thickness measurement module to perform thickness measurement; A thickness measurement module, wherein the thickness measurement module is configured to: transport the thermal conductivity sample to a thermal conductivity measurement chamber, and measure the thickness using the thickness measurement method according to any one of claims 1 to 3; A state determination module, wherein the state determination module is configured to: determine whether the reflective condition of the surface of the thermal conductivity sample after the thickness measurement is completed meets the requirements; if the reflective condition does not meet the requirements, the surface of the thermal conductivity sample is processed to make its surface light energy absorption ratio meet the requirements, and then the irradiated thermal conductivity sample is transferred to the thermal conductivity measurement device; otherwise, the thermal conductivity sample is directly transferred to the thermal conductivity measurement device; A thermal diffusion coefficient measurement module, wherein the thermal diffusion coefficient measurement module is configured to: perform a thermal conductivity measurement test according to the measured thickness of the thermal conductivity sample to obtain the thermal diffusion coefficient of the thermal conductivity sample; And, a calculation module B, wherein the calculation module B is configured to calculate the thermal conductivity of the fuel core after irradiation according to the thermal diffusion coefficient of the thermal conductivity sample.

10. A system for measuring thermal conductivity of a fuel core after irradiation according to claim 9, characterized in that: The thermal conductivity measurement system further comprises: A sample preparation module, wherein the sample preparation module is configured to: prepare a thermal conductivity sample of a fuel core; An irradiation module, wherein the irradiation module is configured to: implement an irradiation experiment of the thermal conductivity sample; A disassembly module, wherein the disassembly module is configured to: take out the irradiated thermal conductivity sample from the irradiation device and transport it to a sample preparation hot chamber; A cleaning and drying module is configured to: clean and dry the irradiated thermal conductivity sample in the sample preparation chamber.

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