Method for testing neutron irradiation resistance of neutron absorbing material

Abstract

The application belongs to the technical field of material detection, and discloses a neutron absorption material neutron irradiation resistance performance test method, which comprises the following steps: preparing a sample of a neutron absorption material to be tested; pretreating the sample; testing the performance of the sample; fixing the sample in a test tank to isolate the sample from the external air environment and water environment; placing the test tank containing the sample into a reactor for irradiation; taking out the sample in the test tank and testing the performance of the taken-out sample; judging whether the neutron absorption material neutron irradiation resistance performance is qualified according to the performance test results before and after irradiation; and thus the objectivity of the evaluation result of the neutron absorption material neutron irradiation resistance performance can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material detection, in particular to a method for testing neutron irradiation resistance of neutron absorbing material. BACKGROUND

[0002] Spent fuel has the characteristics of strong radioactivity and release of a large amount of decay heat, and there is a risk of nuclear criticality, which will cause incalculable disaster if not properly disposed. Safe and reliable management of spent fuel is the key to the future of nuclear energy and the basis for ensuring the safe operation of nuclear power. At present, dry storage tanks are often used to store spent fuel during storage and transportation. Neutron absorbing material plays a crucial role in the process of spent fuel storage and transportation, and is a necessary material for subcritical control and radiation protection of spent fuel during storage and transportation, and is one of the most core materials for spent fuel storage and transportation containers.

[0003] In addition to being a structural and functional integrated material, neutron absorbing material not only needs to have high temperature mechanical properties that meet the requirements, but also needs to have neutron irradiation resistance that meets the requirements. The neutron irradiation caused by the decay of spent fuel will affect the appearance size, B-10 surface density and mechanical properties of the material, so it is necessary to comprehensively and effectively evaluate the neutron irradiation resistance of the neutron absorbing material. At present, when testing the neutron irradiation resistance of the neutron absorbing material, the sample is usually directly placed in the water environment in the reactor for irradiation, which does not correspond to the dry storage and transportation environment of the spent fuel (i.e. the environment during irradiation is different from the actual service conditions of the neutron absorbing material), and the influence of the water environment on the neutron irradiation resistance is not considered, so the neutron irradiation resistance of the neutron absorbing material cannot be objectively reflected. SUMMARY

[0004] The purpose of the present application is to provide a method for testing the neutron irradiation resistance of neutron absorbing material, which can improve the objectivity of the evaluation results of the neutron irradiation resistance of the neutron absorbing material.

[0005] The present application provides a method for testing the neutron irradiation resistance of neutron absorbing material, comprising the steps of:

[0006] A1. preparing a sample of the neutron absorbing material to be tested;

[0007] A2. pretreating the sample;

[0008] A3. testing the performance of the sample;

[0009] A4. fixing the sample in a test tank to isolate the sample from the external air environment and water environment;

[0010] A5. placing the test tank containing the sample in a reactor for irradiation;

[0011] A6. Taking out the sample in the test tank and performing performance test on the taken-out sample;

[0012] A7. Judging whether the neutron irradiation resistance performance of the neutron absorbing material is qualified according to the performance test results before and after irradiation.

[0013] The sample is isolated from the external air environment and water environment by the test tank, and is irradiated in the reactor, and then whether the neutron irradiation resistance performance of the neutron absorbing material is qualified is judged according to the performance test results before and after irradiation. Since the sample is avoided from contacting with the air and water environment during irradiation, the service condition of the neutron absorbing material is simulated, the neutron irradiation resistance performance of the neutron absorbing material under the service condition is comprehensively evaluated, and the objectivity of the evaluation result is better.

[0014] Preferably, the performance test includes appearance detection, size measurement, weight measurement, density measurement, B-10 surface density measurement, room temperature tensile test, high temperature tensile test and impact test.

[0015] The neutron irradiation resistance performance of the neutron absorbing material is evaluated by comprehensively considering the above-mentioned various performance tests, which can more comprehensively and scientifically evaluate the neutron irradiation resistance performance of the neutron absorbing material.

[0016] Preferably, step A1 includes:

[0017] Preparation of the first sample, the room temperature tensile test sample, the high temperature tensile test sample, the impact test sample and the B-10 surface density measurement sample; at least three of each of the samples are prepared.

[0018] Different samples are prepared for different performance tests, which is beneficial to ensure that the shape and size of each sample can meet the test requirements of the corresponding performance test, thereby further improving the objectivity of the evaluation result.

[0019] Preferably, step A2 includes:

[0020] Polishing or sandblasting treatment is performed on the surface of the sample;

[0021] The sample is cleaned by using ethanol in cooperation with ultrasonic wave.

[0022] Since the surface roughness of the material processed by the factory is relatively large and oil stains exist, it will affect the subsequent performance test, so the above-mentioned pretreatment is needed.

[0023] Preferably, step A3 includes:

[0024] A301. Appearance detection, size measurement, weight measurement and density measurement are performed on all the first samples;

[0025] A302. Selecting a portion of the B-10 areal density measurement samples for B-10 areal density measurement;

[0026] A303. Selecting a portion of the room temperature tensile test samples for room temperature tensile test;

[0027] A304. Selecting a portion of the high temperature tensile test samples for high temperature tensile test;

[0028] A305. Selecting a portion of the impact test samples for impact test at room temperature.

[0029] Preferably, step A4 comprises:

[0030] Fixing the first samples that passed the appearance inspection, the B-10 areal density measurement samples that did not undergo B-10 areal density measurement, the room temperature tensile test samples that did not undergo room temperature tensile test, the high temperature tensile test samples that did not undergo high temperature tensile test, and the impact test samples that did not undergo impact test in the test canister.

[0031] Preferably, step A5 comprises:

[0032] Calculating the irradiation time;

[0033] Irradiating the test canister according to the irradiation time.

[0034] Preferably, step A5 comprises:

[0035] Introducing a protective gas into the test canister during irradiation to adjust the temperature inside the test canister.

[0036] Preferably, step A6 comprises:

[0037] A601. Performing appearance inspection, size measurement, weight measurement, and density measurement on the first samples taken out;

[0038] A602. Performing B-10 areal density measurement on the B-10 areal density measurement samples taken out;

[0039] A603. Performing room temperature tensile test on the room temperature tensile test samples taken out;

[0040] A604. Performing high temperature tensile test on the high temperature tensile test samples taken out;

[0041] A605. Performing impact test at room temperature on the impact test samples taken out.

[0042] Preferably, step A7 comprises:

[0043] If one of the first preset conditions is met, it is determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is unqualified, otherwise, it is determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is qualified.

[0044] The first preset condition includes:

[0045] At least one of the first samples taken has unqualified appearance detection;

[0046] At least one of the first samples taken has a thickness reduction amount exceeding a preset maximum reduction threshold;

[0047] At least one of the first samples taken has a length change rate not less than a preset length change threshold;

[0048] At least one of the first samples taken has a width change rate not less than a preset width change threshold;

[0049] At least one of the first samples taken has a weight change rate not less than a preset weight change threshold;

[0050] At least one of the first samples taken has a density change rate not less than a preset density change threshold;

[0051] At least one of the B-10 surface density measurement samples taken has a B-10 surface density less than a preset B-10 surface density threshold;

[0052] At least one of the room temperature tensile test samples taken has a tensile strength at room temperature less than a preset first strength threshold;

[0053] At least one of the room temperature tensile test samples taken has an elongation at break less than a preset first elongation threshold;

[0054] At least one of the high temperature tensile test samples taken has a tensile strength at high temperature less than a preset second strength threshold;

[0055] At least one of the high temperature tensile test samples taken has an elongation at break less than a preset second elongation threshold;

[0056] At least one of the impact test samples taken has an impact energy at room temperature less than a preset impact energy threshold.

[0057] Beneficial effects:

[0058] The neutron absorption material neutron irradiation resistance performance test method provided by the application can isolate the sample from the external air environment and water environment through a test tank, and irradiate the sample in a reactor, and then determine whether the neutron absorption material neutron irradiation resistance performance is qualified according to the performance test results before and after irradiation. Since the sample is prevented from contacting the air and water environment during irradiation, the service conditions of the neutron absorption material are simulated, the neutron absorption material neutron irradiation resistance performance under the service conditions is comprehensively evaluated, and the objectivity of the evaluation result is better. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 The flowchart of the neutron absorption material neutron irradiation resistance performance test method provided by the embodiment of the application.

[0060] Figure 2 The front view of the first sample.

[0061] Figure 3 The front view of the impact test sample.

[0062] Figure 4 The front view of the room temperature tensile test sample and the high temperature tensile test sample.

[0063] Figure 5 The front view of the B-10 surface density measurement sample.

[0064] Figure 6 The structural schematic diagram of the test tank.

[0065] Figure 7 The distribution position diagram of the first layer sample and the fourth layer sample.

[0066] Figure 8 The distribution position diagram of the second layer sample and the third layer sample.

[0067] Label explanation: 1, outer tank body; 2, inner tank body; 3, bottom flange; 4, lower positioning block; 5, lower gasket; 6, clamping block; 7, upper gasket; 8, spring; 9, upper positioning block; 10, top flange; 11, first layer sample; 12, second layer sample; 13, third layer sample; 14, fourth layer sample; 15, neutron detector; 16, air gap; 17, air inlet; 18, air outlet. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0069] It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings. Meanwhile, in the description of the present application, the terms "first", "second", and the like are only used to distinguish description, and cannot be understood as indicating or implying relative importance.

[0070] Please refer to Figure 1 , Figure 1 The method is a method for testing the neutron irradiation resistance of a neutron absorbing material in some embodiments of the present application, comprising the following steps:

[0071] A1. preparing a sample of the neutron absorbing material to be tested;

[0072] A2. pretreating the sample;

[0073] A3. testing the performance of the sample;

[0074] A4. fixing the sample in a test tank to isolate the sample from the external air environment and water environment;

[0075] A5. placing the test tank containing the sample into a reactor for irradiation;

[0076] A6. taking out the sample in the test tank and testing the performance of the taken-out sample;

[0077] A7. judging whether the neutron irradiation resistance of the neutron absorbing material is qualified according to the performance test results before and after irradiation.

[0078] The sample is isolated from the external air environment and water environment by the test tank, and is irradiated in the reactor, and then whether the neutron irradiation resistance of the neutron absorbing material is qualified is judged according to the performance test results before and after irradiation. Since the sample is prevented from contacting the air and water environment during irradiation, the service condition of the neutron absorbing material is simulated, the neutron irradiation resistance of the neutron absorbing material under the service condition is comprehensively evaluated, and the objectivity of the evaluation result is better.

[0079] Preferably, the performance tests include appearance detection, size measurement, weight measurement, density measurement, B-10 (B-10 is an isotope of boron) surface density measurement, room temperature tensile test, high temperature tensile test and impact test.

[0080] The neutron irradiation resistance of the neutron absorbing material can be comprehensively and scientifically evaluated by comprehensively evaluating the various performance tests.

[0081] In some preferred embodiments, step A1 comprises:

[0082] The first sample, the room temperature tensile test sample, the high temperature tensile test sample, the impact test sample and the B-10 surface density measurement sample are prepared; at least three of each sample are prepared.

[0083] Different samples are prepared for different performance tests, which is beneficial to ensure that the shape and size of each sample can meet the test requirements of the corresponding performance test, thereby further improving the objectivity of the evaluation results.

[0084] The following is Figures 2-5 The structure of various samples is described, wherein the length is the size of the left-right direction in the figure, the width is the size of the up-down direction in the figure, and the thickness is the size of the direction perpendicular to the paper in the figure.

[0085] The structure of the first sample is shown in Figure 2 It is a rectangular sheet with a thickness of 1mm-5mm (preferably 2mm), a length of 10mm-50mm (preferably 32mm) and a width of 10mm-50mm (preferably 16mm).

[0086] The structure of the impact test sample is shown in Figure 3 It is a rectangular column with a V-shaped groove in the center of the upper part, the V-shaped groove penetrates through the two sides of the impact test sample in the thickness direction, and the included angle between the two sides of the V-shaped groove is 45°; the length of the impact test sample is 55mm, the width is 10mm, and the thickness is 10mm.

[0087] The structure of the room temperature tensile test sample and the high temperature tensile test sample is shown in Figure 4As shown, the sample includes two connecting portions at two ends and a stretching portion connected between the two connecting portions, the width of the stretching portion is smaller than the width of the connecting portions, and the connecting portions are provided with connecting holes, wherein the width and length of the stretching portion are set according to the relevant provisions of “Metallic Materials - Tensile Testing - Part 1: Method of Test at Room Temperature” (GB / T 228.1-2010) and “Metallic Materials - Tensile Testing - Part 2: Method of Test at Elevated Temperature” (GB / T 228.2-2015); the thickness of the room temperature tensile test sample and the high temperature tensile test sample is 1mm-3mm (preferably 2mm), the length (referring to the total length) is 50mm-150mm (preferably 134.72mm), the width (referring to the maximum width) is 10mm-50mm (preferably 32mm), and the aperture of the connecting hole is 5mm-15mm (preferably 10mm).

[0088] As shown, the structure of the B-10 area density measurement sample is a rectangular sheet with a thickness of 1mm-5mm (preferably 2mm), a length of 10mm-50mm (preferably 10mm), and a width of 10mm-50mm (preferably 10mm). Figure 5

[0089] Generally, when preparing the sample, it is prepared by sampling from the plate or rod of the neutron absorbing material to be tested, and at least three samples of the same kind can be prepared by sampling from different parts (head, tail, middle, edge, etc.) of the plate or rod, so as to take into account the universality and representativeness of the test results.

[0090] In this embodiment, step A2 includes:

[0091] The surface of the sample is polished or sandblasted;

[0092] The sample is cleaned using ethanol and ultrasonic waves.

[0093] Since the surface roughness of the material processed by the factory is relatively large and there may be oil stains, which will affect the subsequent performance test, the above-mentioned pretreatment is needed to reduce the surface roughness of the sample and remove the oil stains.

[0094] When polishing, mechanical milling or mechanical polishing can be used, and if mechanical polishing is used, sandpaper with a fineness of not less than 3000 can be used.

[0095] In fact, the above-mentioned pretreatment method is not limited to reducing the surface roughness of the sample and removing the oil stains, and other existing surface stain removal methods and surface roughness treatment methods can also be used to remove the oil stains and reduce the surface roughness of the sample.

[0096] Specifically, step A3 includes:

[0097] ​A301. Appearance detection, size measurement, weight measurement and density measurement are performed on all the first samples;

[0098] A302. B-10 area density measurement is performed on part of the first samples selected for B-10 area density measurement;

[0099] A303. Room temperature tensile test is performed on part of the first samples selected for room temperature tensile test;

[0100] A304. High temperature tensile test is performed on part of the first samples selected for high temperature tensile test;

[0101] A305. Impact test is performed on part of the first samples selected for impact test at room temperature.

[0102] Wherein, when the appearance detection is performed, the video system or digital camera can be used to check the surface state of the first sample according to the provisions of “Non-destructive Testing of Mechanical Equipment for Nuclear Island of Nuclear Power Plant Part 7: Visual Inspection” (NB / T 20003.7) to check whether there are defects such as corrosion, cracks, scratches, etc. If the first sample has no visible defects such as swelling, corrugation, folding, cracking and scratching, etc., it is determined that the appearance detection of the first sample is qualified, and if the first sample has at least one of the above defects, it is determined that the appearance detection of the first sample is unqualified.

[0103] Wherein, when the size measurement is performed, the length, width and thickness of the first sample are mainly measured. When the length and width are measured, the digital caliper (with an accuracy of not higher than 0.01 mm) can be used to measure the size (length and width) of the first sample at least at three positions and take the average value as the measurement result, and when the thickness is measured, the inductance micrometer (with an accuracy of not higher than 0.001 m) can be used to measure the thickness of the first sample at least at nine positions and take the average value as the measurement result.

[0104] Wherein, when the weight measurement is performed, the measurement can be performed according to the provisions of “Electronic Balance” (GB / T 26497-2011), and the Mettler XSR204 electronic balance (with an accuracy of ±0.1 mg) can be used to measure the dry weight and wet weight of the first sample.

[0105] Wherein, when the density measurement is performed, the measurement can be performed according to the provisions of “Method for Determining the Density of Dense Sintered Metal Materials and Hard Alloys” (GB / T 3850-2015), and the density of the first sample is calculated according to the dry weight and wet weight measurement results.

[0106] Wherein, when the B-10 area density measurement is carried out, the boron carbide mass fraction can be measured according to the provisions of the Standard Test Method for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Boron Carbide, Nuclear-Purity Grade (ASTM C791-2011) or the applicable parts of the corresponding national standard or other comparable test methods, and the B-10 isotope content can be measured according to the Standard Test Method for Constituents in Composite Materials (ASTM D3171-15) or the corresponding national standard or other comparable test methods, and then the B-10 area density is calculated according to the boron carbide mass fraction and the B-10 isotope content (the specific calculation process is prior art, which is not limited here).

[0107] Wherein, when the room temperature tensile test is carried out, the test can be carried out according to the provisions of Metallic Materials-Tensile Testing-Part 1: Method of Test at Room Temperature (GB / T 228.1-2010), and the tensile strength and elongation at break of the room temperature tensile test sample can be obtained by tensile test on a universal material testing machine.

[0108] Wherein, when the high temperature tensile test is carried out, the test can be carried out according to the provisions of Metallic Materials-Tensile Testing-Part 2: Method of Test at Elevated Temperature (GB / T 228.2-2015), the high temperature tensile test temperature is 450℃, and the tensile strength and elongation at break of the high temperature tensile test sample can be obtained by tensile test on a universal material testing machine.

[0109] Wherein, when the impact test is carried out, the test can be carried out according to the provisions of Metallic Materials Charpy Pendulum Impact Test Method (GB / T 229-2020), and the impact energy of the impact test sample at room temperature can be tested.

[0110] Further, step A4 comprises:

[0111] The first sample that passes the appearance detection, the B-10 area density measurement sample that has not been subjected to B-10 area density measurement, the room temperature tensile test sample that has not been subjected to room temperature tensile test, the high temperature tensile test sample that has not been subjected to high temperature tensile test, and the impact test sample that has not been subjected to impact test are fixed in the test tank.

[0112] The samples that have been subjected to B-10 area density measurement, room temperature tensile test, high temperature tensile test and impact test will be damaged to a certain extent, resulting in changes in shape and / or mechanical properties, and therefore cannot be used for subsequent tests, so only the B-10 area density measurement sample that has not been subjected to B-10 area density measurement, the room temperature tensile test sample that has not been subjected to room temperature tensile test, the high temperature tensile test sample that has not been subjected to high temperature tensile test, and the impact test sample that has not been subjected to impact test are used for subsequent tests.

[0113] In order to comprehensively investigate the influence of irradiation on the performance of the tested sample, the performance of the sample after irradiation needs to be tested, so different size samples of different appearances need to be placed in the test tank, and the neutron irradiation dose of the samples in different positions may be different. In order to ensure that the neutron dose of the sample irradiation is the same, the samples need to be arranged in a specific order and space.

[0114] For example Figure 6 、 Figure 7 、 Figure 8 The arrangement mode is shown in the figure, wherein the test tank comprises an outer tank body 1 and an inner tank body 2 arranged coaxially, and a sample mounting cavity is formed between the outer tank body 1 and the inner tank body 2. From bottom to top, the sample mounting cavity is sequentially provided with a bottom flange 3, a lower positioning block 4, a lower gasket 5, three layers of clamping blocks 6, an upper gasket 7, a spring 8, an upper positioning block 9 and a top flange 10. The samples are arranged in four layers in the sample mounting cavity. The first layer of samples 11 is arranged between the upper gasket 7 and the uppermost clamping block 6, the second layer of samples 12 is arranged between the uppermost clamping block 6 and the middle clamping block 6, the third layer of samples 13 is arranged between the middle clamping block 6 and the lowermost clamping block 6, and the fourth layer of samples 14 is arranged between the lowermost clamping block 6 and the lower gasket 5. The two ends of the spring 8 are respectively in abutment with the upper positioning block 9 and the upper gasket 7, so as to press and fix the samples in each layer (the upper gasket 7 and the uppermost clamping block 6 clamp the upper and lower ends of the first layer of samples 11, the uppermost clamping block 6 and the middle clamping block 6 clamp the upper and lower ends of the second layer of samples 12, the middle clamping block 6 and the lowermost clamping block 6 clamp the upper and lower ends of the third layer of samples 13, and the lowermost clamping block 6 and the lower gasket 5 clamp the upper and lower ends of the fourth layer of samples 14. It should be noted that Figure 6 In order to facilitate the display of the positional relationship between the components, the clamping block 6 is drawn as a plate with uniform thickness, but in fact the thickness of the clamping block 6 at each position is related to the length of the corresponding sample, so that it can be in abutment with the corresponding sample end), through the pressing force of the spring 8, the position of each sample relative to the test tank can be ensured not to change due to movement of the test tank.

[0115] In Figure 7 , the first layer of samples 11 and the fourth layer of samples 14 each comprise a first sample, a high-temperature tensile test sample, a room-temperature tensile test sample and a B-10 face density measurement sample. Since these samples are all plate-shaped, they are stacked on each other and arranged in four groups, two groups are arranged on the side facing the neutron incident direction (referring to the neutron incident direction when irradiation is performed, in Figure 7 , the neutron incident direction is from top to bottom), and the other two groups are arranged on the side facing away from the neutron incident direction. The stacked thickness of the two groups of samples on the side facing away from the neutron incident direction is smaller than that of the two groups of samples on the side facing the neutron incident direction, so as to ensure that each sample is uniformly irradiated; the specific number of stacks can be arranged according to actual needs.

[0116] InFigure 8 In the specific embodiment, the second layer sample 12 and the third layer sample 13 are both impact test samples, and the second layer sample 12 and the third layer sample 13 are both divided into two groups, one group is uniformly distributed on the side facing the neutron incident direction, and the other group is uniformly distributed on the side facing away from the neutron incident direction, and the number of samples uniformly distributed on the side facing the neutron incident direction is more than the number of samples uniformly distributed on the side facing away from the neutron incident direction, so as to ensure that each sample is uniformly irradiated; the specific number can be set according to actual needs.

[0117] In some embodiments, see Figure 7 , In some embodiments, see Figure 8 , the outer tank body 1 and the inner tank body 2 are connected by two radial connecting plates, and the two radial connecting plates divide the sample mounting cavity into a first mounting cavity on the side facing the neutron incident direction and a second mounting cavity on the side facing away from the neutron incident direction, and each layer of clamping block 6 includes two sub-clamping blocks located in the first mounting cavity and the second mounting cavity, respectively. Therefore, the samples on the side facing the neutron incident direction mentioned in the foregoing are arranged in the first mounting cavity, and the samples on the side facing away from the neutron incident direction are arranged in the second mounting cavity.

[0118] Preferably, step A5 comprises:

[0119] calculating the irradiation time;

[0120] irradiating the test tank according to the irradiation time.

[0121] In order to more truly test the influence of neutron irradiation on the performance of the neutron absorbing material, the test tank is placed in the reactor for neutron irradiation. The irradiation time is an irradiation parameter that needs to be focused on, and can be calculated according to the target neutron fluence and fluence rate, and the specific calculation method is prior art, which will not be described here. Among them, the target neutron fluence and fluence rate here mainly refer to the fast neutron (E≥1.0 MeV) fluence target value and the fast neutron (E≥1.0 MeV) fluence rate, wherein the fast neutron (E≥1.0 MeV) fluence target value can be set according to actual needs, and is generally 1×10 15 n / cm 2 -3×10 19 n / cm 2 , and the fast neutron (E≥1.0 MeV) fluence rate can be obtained in advance through experiments.

[0122] After the irradiation time is calculated, the test tank is taken out after the duration of irradiation in the reactor reaches the irradiation time.

[0123] Wherein, a fast neutron detector can also be arranged in the test tank to detect the real fast neutron fluence, if the deviation between the real fast neutron fluence and the fast neutron fluence target value is too large (out of the pre-set tolerance range, which can be set according to actual needs), retest (steps A1-A7) is performed, and the irradiation time is adjusted according to the deviation between the real fast neutron fluence and the fast neutron fluence target value (for example, the real fast neutron fluence is divided by the irradiation time to obtain the average fluence rate, then the deviation is multiplied by -1 and divided by the average fluence rate to obtain the compensation time, and finally the recalculated irradiation time is added to the compensation time when retesting). Wherein, the neutron detector can be a high-purity (99.99% mass fraction) Fe, Cu, Ni, Ti wire, preferably 1mm in diameter, for example Figure 7 、 Figure 8 As shown in FIGS. 15 and 16, at least one neutron detector 15 can be arranged at each layer of the sample (for example, one on the side facing the neutron incident direction and one on the side facing away from the neutron incident direction), which can be taken out of the test tank after irradiation for neutron activation analysis detection to obtain the real fast neutron fluence (the average of the fast neutron fluences measured by each neutron detector can be taken as the real fast neutron fluence).

[0124] In some preferred embodiments, step A5 further comprises:

[0125] During irradiation, protective gas is introduced into the test tank to adjust the temperature inside the test tank.

[0126] A temperature sensor can be arranged in the test tank to monitor the temperature inside the test tank in real time, when the detected temperature exceeds the pre-set range, protective gas is introduced into one end of the test tank and flows out from the other end of the test tank, and the flow rate of the protective gas is adjusted to keep the temperature inside the test tank within the pre-set range. The protective gas can be but is not limited to nitrogen, argon or helium. For example Figures 6-8 In this case, each clamping block 6 has an air permeable gap 16 between the inner wall of the outer tank body 1 and the inner tank body 2, the upper gasket 7, the upper positioning block 9 and the top flange 10 are provided with an air inlet 17, and the bottom flange 3, the lower positioning block 4 and the lower gasket 5 are provided with an air outlet 18. Protective gas can be introduced from the air inlet 17, and the protective gas flows down from the air permeable gap 16 and finally flows out from the air outlet 18.

[0127] Preferably, step A6 comprises:

[0128] A601. Appearance detection, size measurement, weight measurement and density measurement are performed on the removed first sample (for details, refer to the foregoing description);

[0129] A602. B-10 areal density measurement is performed on the removed B-10 areal density measurement sample (the specific process is referred to the foregoing);

[0130] A603. Room temperature tensile test is performed on the removed room temperature tensile test sample (the specific process is referred to the foregoing);

[0131] A604. High temperature tensile test is performed on the removed high temperature tensile test sample (the specific process is referred to the foregoing);

[0132] A605. Impact test is performed on the removed impact test sample at room temperature (the specific process is referred to the foregoing).

[0133] It should be noted that the sample needs to be removed in the hot cell, therefore, before step A601, there is also a step of removing the test tank from the reactor and standing until the radioactive neutron dose decays to the standard for entering the hot cell, and transferring the test tank to the hot cell for sample removal.

[0134] Further, step A7 comprises:

[0135] If one of the first preset conditions is met, it is determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is unqualified, otherwise, it is determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is qualified;

[0136] The first preset condition comprises:

[0137] (1) In the removed first samples, at least one first sample fails in appearance detection;

[0138] (2) In the removed first samples, at least one first sample has a thickness thinning amount exceeding a preset maximum thinning threshold (the maximum thinning threshold can be set according to actual needs, for example, 0.2 mm, but not limited thereto);

[0139] (3) In the removed first samples, at least one first sample has a length change rate not less than a preset length change threshold (the length change threshold can be set according to actual needs, for example, 2%, but not limited thereto);

[0140] (4) In the removed first samples, at least one first sample has a width change rate not less than a preset width change threshold (the width change threshold can be set according to actual needs, for example, 2%, but not limited thereto);

[0141] (5) In the removed first samples, at least one first sample has a weight change rate not less than a preset weight change threshold (the weight change threshold can be set according to actual needs, for example, 3%, but not limited thereto);

[0142] (6) the rate of change of density of at least one of the first samples is not less than a preset density change threshold (the density change threshold can be set according to actual needs, for example, 3%, but is not limited thereto);

[0143] (7) the B-10 face density of at least one of the B-10 face density measurement samples is less than a preset B-10 face density threshold (the B-10 face density threshold can be set according to actual needs, for example, 0.00704 g / cm 2 , but is not limited thereto);

[0144] (8) the tensile strength at room temperature of at least one of the room temperature tensile test samples is less than a preset first strength threshold (the first strength threshold can be set according to actual needs, for example, 100 MPa, but is not limited thereto);

[0145] (9) the elongation at break of at least one of the room temperature tensile test samples is less than a preset first elongation threshold (the first elongation threshold can be set according to actual needs, for example, 1%, but is not limited thereto);

[0146] (10) the tensile strength at high temperature (450°C) of at least one of the high temperature tensile test samples is less than a preset second strength threshold (the second strength threshold can be set according to actual needs, for example, 58 MPa, but is not limited thereto);

[0147] (11) the elongation at break of at least one of the high temperature tensile test samples is less than a preset second elongation threshold (the second elongation threshold can be set according to actual needs, for example, 1%, but is not limited thereto);

[0148] (12) the impact energy at room temperature of at least one of the impact test samples is less than a preset impact energy threshold (the impact energy threshold can be set according to actual needs, for example, 8 J, but is not limited thereto).

[0149] That is, as long as at least one of conditions (1)-(12) is met, it is determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is unqualified, otherwise, it is determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is qualified. That is, only when all the samples are tested qualified in the corresponding performance tests, it is finally determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is qualified, so as to ensure that the neutron absorbing material determined to be qualified in the neutron irradiation resistance performance can reliably meet the performance requirements of the neutron absorbing material during spent fuel storage and transportation.

[0150] In practical applications, in step A3, if it is detected that the unqualified rate of at least one of the B-10 area density measurement sample, the impact test sample, the room temperature tensile test sample and the high temperature tensile test sample exceeds a preset proportion threshold value (which can be set according to actual needs), it can be directly determined that the neutron irradiation resistance performance of the neutron absorbing material to be tested is unqualified, so that subsequent steps do not need to be executed. Here, the B-10 area density measurement sample is unqualified refers to that the B-10 area density of the B-10 area density measurement sample is less than a preset B-10 area density threshold value, the impact test sample is unqualified refers to that the impact work of the impact test sample at room temperature is less than a preset impact work threshold value; the room temperature tensile test sample is unqualified refers to that the tensile strength of the room temperature tensile test sample at room temperature is less than a preset first strength threshold value, or the elongation after fracture is less than a preset first elongation threshold value; the high temperature tensile test sample is unqualified refers to that the tensile strength of the high temperature tensile test sample at high temperature is less than a preset second strength threshold value, or the elongation after fracture is less than a preset second elongation threshold value.

[0151] Embodiment one

[0152] In embodiment one, the neutron absorbing material to be tested is an aluminum-based boron carbide neutron absorbing material, wherein the mass fraction of B4C particles is 10 wt%, and the B-10 abundance is 19.6%-20.0%. When the test method described above is used for testing, the neutron irradiation conditions are as follows: the fast neutron (E≥1.0 MeV) fluence rate is 8.7×10 12 n / cm -2 ∙s -1 , the fast neutron (E≥1.0 MeV) fluence target value is 2×10 19 n / cm 2 -3×10 19 n / cm 2 , the irradiation time is 29 days, the temperature does not exceed 150 ℃, all the first samples are taken and one B-10 area density measurement sample, one room temperature tensile test sample, one high temperature tensile test sample and one impact test sample are taken for performance testing before irradiation, and three first samples, three B-10 area density measurement samples, three room temperature tensile test samples, three high temperature tensile test samples and three impact test samples that pass the appearance detection are selected for irradiation.

[0153] The conditions for the neutron irradiation resistance performance of the neutron absorbing material to be qualified are as follows: all the first samples after irradiation pass the appearance detection, the thickness reduction of all the first samples before and after irradiation is ≤0.2 mm, the change rate of the length of all the first samples before and after irradiation is <2%, the change rate of the width of all the first samples before and after irradiation is <2%, the change rate of the weight of all the first samples before and after irradiation is <3%, the change rate of the density of all the first samples before and after irradiation is <3%, and the B-10 area density of all the B-10 area density measurement samples before and after irradiation is >0.00704 g / cm2 , the impact energy of all the impact test samples before and after irradiation is ≥8J, the tensile strength at room temperature of all the room temperature tensile test samples before and after irradiation is ≥100Mpa and the elongation at break is ≥1%, and the tensile strength at 450℃ of all the high temperature tensile test samples before and after irradiation is ≥58Mpa and the elongation at break is ≥1%.

[0154] After irradiation, all the first samples have no visible defects such as swelling, corrugation, folding, cracking and scratches; the maximum thickness increase of each first sample is 0.022mm (i.e. no thinning), and the thickness change rate is 1.108%; the maximum weight increase of each first sample is 0.008g, and the weight change rate is 0.296% (less than 3%); the maximum density change of each first sample is a decrease of 0.031g / cm3, and the density change rate is 1.145% (less than 3%); therefore, each first sample is qualified.

[0155] The mechanical properties of the room temperature tensile test samples at room temperature: the unirradiated tensile strength Rm is 234 MPa (greater than 100MPa), the yield strength R P0.2 is 190 MPa, and the elongation at break is 12.5% (greater than 1%), and the irradiated tensile strength Rm is 270 Mpa (greater than 100MPa), the yield strength R P0.2 is 223 MPa, and the elongation at break is 6.0% (greater than 1%); therefore, each room temperature tensile test sample is qualified.

[0156] The mechanical properties of the high temperature tensile test samples at 450℃: the unirradiated tensile strength Rm is 86 MPa (greater than 58MPa), the yield strength R P0.2 is 76 MPa, and the elongation at break is 5.5% (not less than 1%), and the irradiated tensile strength Rm is 89 Mpa (greater than 58MPa), the yield strength R P0.2 is 83 MPa, and the elongation at break is 1.0% (not less than 1%); therefore, each high temperature tensile test sample is qualified.

[0157] The impact energy of the unirradiated impact test samples is 14J (greater than 8J), and the impact energy of the irradiated impact test samples is 14J (greater than 8J); therefore, each impact test sample is qualified.

[0158] Before irradiation, the minimum B-10 surface density of each B-10 surface density measurement sample is 0.00785g / cm 2 (>0.00704g / cm 2 ); after irradiation, the minimum B-10 surface density of each B-10 surface density measurement sample is 0.00746g / cm 2 (>0.00704g / cm2 ); thus, each B-10 areal density measurement sample is qualified.

[0159] Since each sample is qualified, it is finally determined that the neutron irradiation resistance performance of the aluminum-based boron carbide neutron absorbing material is qualified.

[0160] Example Two

[0161] In Example Two, the neutron absorbing material to be tested is an aluminum-based boron carbide neutron absorbing material, in which the mass fraction of B4C particles is 10 wt%, and the B-10 abundance is 19.6%-20.0%. After the material is aged at a high temperature of 460 ℃ for 140 h, various samples are prepared for testing. When the testing method described above is used to test, the neutron irradiation conditions are as follows: the fast neutron (E≥1.0 MeV) fluence rate is 8.7×10 12 n / cm -2 ·s -1 , the fast neutron (E≥1.0 MeV) fluence target value is 2×10 19 n / cm 2 -3×10 19 n / cm 2 , the irradiation time is 29 days, the temperature does not exceed 150 ℃, all the first samples are taken and one B-10 areal density measurement sample, one room temperature tensile test sample, one high temperature tensile test sample and one impact test sample are taken for performance testing before irradiation, and three first samples, three B-10 areal density measurement samples, three room temperature tensile test samples, three high temperature tensile test samples and three impact test samples that pass the appearance detection are selected for irradiation.

[0162] The conditions for the neutron irradiation resistance performance of the neutron absorbing material to be qualified are as follows: after irradiation, all the first samples pass the appearance detection, the thickness reduction of all the first samples before and after irradiation is ≤0.2 mm, the change rate of the length of all the first samples before and after irradiation is <2%, the change rate of the width of all the first samples before and after irradiation is <2%, the change rate of the weight of all the first samples before and after irradiation is <3%, the change rate of the density of all the first samples before and after irradiation is <3%, the B-10 areal density of all the B-10 areal density measurement samples before and after irradiation is >0.00704 g / cm 2 , the impact energy of all the impact test samples at room temperature before and after irradiation is ≥8 J, the tensile strength of all the room temperature tensile test samples at room temperature before and after irradiation is ≥100 Mpa and the elongation after fracture is ≥1%, and the tensile strength of all the high temperature tensile test samples at 450 ℃ before and after irradiation is ≥58 Mpa and the elongation after fracture is ≥1%.

[0163] After irradiation, all first samples had no visible defects such as swelling, ripples, folds, cracks and scratches; the maximum thickness increase of each first sample was 0.010mm (i.e. no thinning), and the thickness change rate was 0.504%; the maximum weight increase of each first sample was 0.009g, and the weight change rate was 0.332% (less than 3%); the maximum density change of each first sample was a decrease of 0.035g / cm3, and the density change rate was 1.292% (less than 3%); therefore, each first sample was qualified.

[0164] Mechanical properties of room temperature tensile test samples at room temperature: unirradiated tensile strength Rm is 231 MPa (greater than 100 MPa), yield strength R P0.2 The tensile strength after irradiation is 196 MPa, the elongation after fracture is 17.5% (greater than 1%), the tensile strength Rm after irradiation is 272 MPa (greater than 100 MPa), the yield strength R P0.2 The tensile strength is 232 MPa and the elongation after break is 4.5% (greater than 1%); therefore, all room temperature tensile test samples are qualified.

[0165] Mechanical properties of high temperature tensile test samples at 450℃: unirradiated tensile strength Rm is 76 MPa (greater than 58 MPa), yield strength R P0.2 The tensile strength after irradiation is 69 MPa, the elongation after fracture is 5.5% (not less than 1%), the tensile strength Rm after irradiation is 74 MPa (greater than 58 MPa), the yield strength R P0.2 The tensile strength is 67 MPa and the elongation after break is 1.5% (not less than 1%); therefore, all high-temperature tensile test samples are qualified.

[0166] The impact energy of the unirradiated impact test sample is 13J (greater than 8J), and the impact energy of the irradiated impact test sample is 13J (greater than 8J); therefore, all impact test samples are qualified.

[0167] Before irradiation, the minimum B-10 areal density of each B-10 areal density measurement sample is 0.00803 g / cm 2 (>0.00704g / cm 2 After irradiation, the minimum B-10 areal density of each B-10 areal density measurement sample is 0.00749 g / cm 2 (>0.00704g / cm 2 ); Therefore, all B-10 areal density measurement samples are qualified.

[0168] Since all samples were qualified, it was finally determined that the neutron irradiation resistance of the aluminum-based boron carbide neutron absorbing material was qualified.

[0169] Example 3

[0170] In Example Three, the neutron absorbing material to be tested is an aluminum-based boron carbide neutron absorbing material, wherein the mass fraction of B4C particles is 10 wt%, and the B-10 abundance is 19.6%-20.0%. The welded state material is prepared by using friction stir welding processing, and various samples are extracted from the weld of the neutron absorbing material for testing. When the samples are tested by using the test method described above, the neutron irradiation conditions are as follows: the fast neutron (E≥1.0 MeV) fluence rate is 8.7×10 12 n / cm -2 ∙s -1 , the fast neutron (E≥1.0 MeV) fluence target value is 2×10 19 n / cm 2 -3×10 19 n / cm 2 , the irradiation time is 29 days, the temperature is not more than 150 ℃, all the first samples and one B-10 surface density measurement sample, one room temperature tensile test sample, one high temperature tensile test sample, and one impact test sample are taken for performance testing before irradiation, and three first samples, three B-10 surface density measurement samples, three room temperature tensile test samples, three high temperature tensile test samples, and three impact test samples that pass the appearance detection are selected for irradiation.

[0171] The conditions for the neutron irradiation resistance performance of the neutron absorbing material to be qualified are as follows: after irradiation, all the first samples pass the appearance detection, the thickness reduction of all the first samples before and after irradiation is ≤0.2 mm, the change rate of the length of all the first samples before and after irradiation is <2%, the change rate of the width of all the first samples before and after irradiation is <2%, the change rate of the weight of all the first samples before and after irradiation is <3%, the change rate of the density of all the first samples before and after irradiation is <3%, the B-10 surface density of all the B-10 surface density measurement samples before and after irradiation is >0.00704 g / cm 2 , the impact energy of all the impact test samples at room temperature before and after irradiation is ≥8 J, the tensile strength of all the room temperature tensile test samples at room temperature before and after irradiation is ≥100 Mpa and the elongation after fracture is ≥1%, and the tensile strength of all the high temperature tensile test samples at 450 ℃ before and after irradiation is ≥58 Mpa and the elongation after fracture is ≥1%.

[0172] After irradiation, all the first samples have no visible defects such as swelling, corrugation, folding, cracking, and scratches; the maximum thickness increase of each first sample is 0.026 mm (i.e., no thickness reduction), and the thickness change rate is 1.309%; the maximum weight increase of each first sample is 0.01 g, and the weight change rate is 0.37% (less than 3%); the maximum density change of each first sample is a decrease of 0.020 g / cm3, and the density change rate is 0.742% (less than 3%); therefore, each first sample is qualified.

[0173] The mechanical properties of the room temperature tensile test sample at room temperature: the unirradiated tensile strength Rm was 193 MPa (greater than 100 MPa), the yield strength R P0.2 was 142 MPa, the elongation after fracture was 7.5% (greater than 1%), the irradiated tensile strength Rm was 252 MPa (greater than 100 MPa), the yield strength R P0.2 was 202 MPa, and the elongation after fracture was 3.0% (greater than 1%); thus, each room temperature tensile test sample was qualified.

[0174] The mechanical properties of the high temperature tensile test sample at 450°C: the unirradiated tensile strength Rm was 57 MPa (less than 58 MPa), the yield strength R P0.2 was 54 MPa, the elongation after fracture was 1.0% (not less than 1%), the irradiated tensile strength Rm was 81 MPa (greater than 58 MPa), the yield strength R P0.2 was 54 MPa, and the elongation after fracture was 1.0% (not less than 1%); since the unirradiated tensile strength was less than 58 MPa, the high temperature tensile test sample was unqualified.

[0175] The impact energy of the unirradiated impact test sample was 12 J (greater than 8 J), and the impact energy of the irradiated impact test sample was 11 J (greater than 8 J); thus, each impact test sample was qualified.

[0176] Before irradiation, the minimum B-10 surface density of each B-10 surface density measurement sample was 0.00803 g / cm 2 (> 0.00704 g / cm 2 ); after irradiation, the minimum B-10 surface density of each B-10 surface density measurement sample was 0.00753 g / cm 2 (> 0.00704 g / cm 2 ); thus, each B-10 surface density measurement sample was qualified.

[0177] Since the high temperature tensile test sample was unqualified, it was finally determined that the neutron irradiation resistance performance of the aluminum-based boron carbide neutron absorbing material was unqualified.

[0178] In this document, the terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0179] The above merely provides an example of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for testing the neutron irradiation resistance of a neutron absorbing material, characterized in that: Including steps: A1. Prepare a sample of neutron absorbing material to be tested; A2. Pre-treating the sample; A3. Performance testing of the samples; A4. The sample is fixed in the test tank to isolate the sample from the external air and water environment; A5. The test tank containing the sample is placed in the reactor for irradiation; A6. Remove the sample from the test tank and perform a performance test on the sample removed; A7. Determine whether the neutron absorbing material's neutron radiation resistance is acceptable based on the performance test results before and after irradiation. Step A1 includes: Prepare a first sample, a room temperature tensile test sample, a high temperature tensile test sample, an impact test sample, and a B-10 areal density measurement sample; wherein the first sample is used for appearance inspection, dimensional measurement, weight measurement, and density measurement; Step A5 includes: During the irradiation process, a protective gas is introduced into the test tank to regulate the temperature inside the test tank: a temperature sensor is provided in the test tank to monitor the temperature inside the test tank in real time, and when the temperature is detected to exceed a preset range, a protective gas is introduced into one end of the test tank and the protective gas is discharged from the other end of the test tank, and the flow rate of the protective gas is adjusted to maintain the temperature inside the test tank within the preset range; Since the sample was prevented from contacting with air and water environment during the irradiation process, the service conditions of neutron absorbing materials were simulated.

2. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 1, characterized in that: The performance tests include appearance inspection, dimension measurement, weight measurement, density measurement, B-10 areal density measurement, room temperature tensile test, high temperature tensile test and impact test.

3. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 2, characterized in that: In step A1, at least three of each sample are prepared.

4. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 1, wherein: Step A2 includes: Grinding or sandblasting the surface of the sample; The samples were cleaned using ethanol and ultrasonic waves.

5. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 3, characterized in that: Step A3 includes: A301 all the first sample appearance inspection, size measurement, weight measurement and density measurement; A302. Select some of the B-10 surface density measurement samples for B-10 surface density measurement; A303. Select some of the room temperature tensile test samples for room temperature tensile test; A304. Select some of the high temperature tensile test samples for high temperature tensile test; A305. Select some of the impact test samples and conduct impact tests at room temperature.

6. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 5, characterized in that: Step A4 includes: The first sample that passed the appearance inspection, the B-10 areal density measurement sample that did not undergo B-10 areal density measurement, the room temperature tensile test sample that did not undergo room temperature tensile test, the high temperature tensile test sample that did not undergo high temperature tensile test, and the impact test sample that did not undergo impact test are fixed in the test tank.

7. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 1, characterized in that: Step A5 includes: Calculate irradiation time; The test can is irradiated according to the irradiation time.

8. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 3, characterized in that: Step A6 includes: A601. The first sample removed was subjected to appearance inspection, size measurement, weight measurement and density measurement; A602. The B-10 surface density measurement sample was taken out for B-10 surface density measurement; A603. The room temperature tensile test sample was taken out and subjected to a room temperature tensile test; A604. The high temperature tensile test sample was removed and subjected to a high temperature tensile test; A605. Perform an impact test on the impact test sample taken out at room temperature.

9. The method for testing the neutron irradiation resistance of a neutron absorbing material according to claim 8, characterized in that: Step A7 includes: If one of the first preset conditions is met, it is determined that the neutron radiation resistance performance of the neutron absorbing material to be tested is unqualified; otherwise, it is determined that the neutron radiation resistance performance of the neutron absorbing material to be tested is qualified; The first preset condition includes: At least one of the first samples taken out fails the appearance inspection; Among the first samples taken out, the thickness reduction of at least one of the first samples exceeds a preset maximum thinning threshold; Among the first samples taken out, a length change rate of at least one of the first samples is not less than a preset length change threshold; Among the first samples taken out, a width change rate of at least one of the first samples is not less than a preset width change threshold; Among the first samples taken out, a weight change rate of at least one of the first samples is not less than a preset weight change threshold; Among the first samples taken out, a density change rate of at least one of the first samples is not less than a preset density change threshold; Among the B-10 areal density measurement samples taken out, the B-10 areal density of at least one B-10 areal density measurement sample is less than a preset B-10 areal density threshold; Among the room temperature tensile test samples taken out, the tensile strength of at least one room temperature tensile test sample at room temperature is less than a preset first strength threshold; Among the room temperature tensile test samples taken out, the elongation after fracture of at least one room temperature tensile test sample is less than a preset first elongation threshold value; Among the high-temperature tensile test samples taken out, the tensile strength of at least one high-temperature tensile test sample at high temperature is less than a preset second strength threshold; Among the high-temperature tensile test samples taken out, the elongation after fracture of at least one high-temperature tensile test sample is less than a preset second elongation threshold value; Among the impact test samples taken out, the impact energy of at least one impact test sample at room temperature is less than a preset impact energy threshold.

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