Preparation method of proficiency testing soil sample for radionuclide analysis

Abstract

The invention relates to a preparation method of a proficiency testing soil sample for radionuclide analysis. The method belongs to the technical field of radiation environment monitoring, and comprises the following steps: preparing a first soil matrix and a second soil matrix for standard mixing operation, and placing the first soil matrix in a first container; dropping a radionuclide standard solution into a predetermined area of the first soil matrix, wherein the radionuclide standard solution is not in contact with the inner wall of the first container; drying the first soil matrix dripped with the radionuclide standard solution until the first soil matrix is in loose fine powder; transferring the dried first soil matrix to a second container, and transferring the second soil matrix to the second container through the first container; the first soil matrix and the second soil matrix in the second container are subjected to sample mixing treatment, and a soil sample is obtained. According to the method provided by the invention, the radionuclide and the soil can be mixed more uniformly, and the uniformity of the proficiency testing sample is improved.

Description

Technical Field

[0001] The invention relates to the technical field of radiation environment monitoring, in particular to a method for preparing soil samples for capability verification of radionuclide analysis. Background Art

[0002] With the widespread application of nuclear energy technology and the increasing concern about nuclear waste disposal, the monitoring of radionuclides in soil has become particularly important. As an important part of the ecosystem, soil directly affects the growth of crops, environmental quality and human health. Therefore, the monitoring of radionuclides in soil not only helps to assess the impact of nuclear pollution on the environment, but also ensures food safety and public health.

[0003] Radionuclides in soil may come from natural local radiation, nuclear testing, nuclear accidents or waste disposal. Long-term exposure to high doses of radioactive substances may cause radiation damage to organisms and lead to various health problems, including cancer and genetic diseases. Therefore, monitoring radionuclides in soil helps to timely detect and assess environmental pollution, take appropriate protective measures, and reduce the risks of radiation to ecology and human health.

[0004] There is a shortage of radionuclide standard materials in soil. In laboratory internal quality control, inter-laboratory comparison and proficiency verification, the analysis of radionuclides in soil samples is prepared by the standard addition method. However, since some radionuclides do not have solid standard materials, the following problems exist when mixing radionuclide standard solutions with soil samples:

[0005] The proficiency verification sample (soil sample) used to evaluate the laboratory's proficiency in radionuclide analysis in soil is prepared by the standard addition method. However, since it is impossible to ensure that the soil and the radionuclide solution are evenly mixed, the uniformity of the proficiency verification sample is low. During the preparation of the soil sample, there is a situation where the radionuclide solution may be lost on the wall of the vessel, thereby affecting the accuracy of the assessment. In addition, the soil is easily affected by moisture, which can easily affect the activity concentration value of the radionuclides in the soil sample. Therefore, the present application provides a method for preparing a proficiency verification soil sample for radionuclide analysis.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0007] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for preparing soil samples for proficiency testing of radionuclide analysis, which can improve the uniformity and evaluation accuracy of proficiency testing samples and ensure that the activity concentration value is not affected.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is: a method for preparing a soil sample for capability verification of radionuclide analysis, comprising the following steps: preparing a first soil matrix and a second soil matrix for a doping operation, wherein the first soil matrix is ​​placed in a first container; dropping a radionuclide standard solution to a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container; drying the first soil matrix with the radionuclide standard solution dropped thereon until the first soil matrix is ​​in a loose fine powder state; transferring the dried first soil matrix to a second container, and transferring the second soil matrix to the second container through the first container; mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample.

[0009] Preferably, dripping the radionuclide standard solution to a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container, includes at least one of the following: dripping the radionuclide standard solution to the central area of ​​the surface of the first soil matrix contained in the first container, and the radionuclide standard solution does not contact the inner wall of the first container; or, dripping the radionuclide standard solution to the geometric center area of ​​the first soil matrix contained in the first container, and the radionuclide standard solution does not contact the inner wall of the first container; or, dripping the radionuclide standard solution to the geometric center area of ​​the first container, and the radionuclide standard solution does not contact the inner wall of the first container.

[0010] Preferably, the step of dripping the radionuclide standard solution to a predetermined area of ​​the first soil matrix without contacting the radionuclide standard solution with the inner wall of the first container comprises: using a pipette to absorb the radionuclide standard solution, and dripping the radionuclide standard solution to a predetermined area of ​​the first soil matrix without contacting the radionuclide standard solution with the inner wall of the first container.

[0011] Preferably, the first container is a beaker and the second container is a mixing barrel; wherein, preparing the first soil matrix and the second soil matrix for the doping operation comprises: weighing a soil matrix of a first weight value and placing it into the mixing barrel; weighing a first soil matrix of a second weight value from the mixing barrel and transferring it to the beaker, and taking out a second soil matrix of a third weight value for standby use, wherein the first soil matrix and the second soil matrix are the same soil matrix.

[0012] Preferably, the mixing of the first soil matrix and the second soil matrix in the second container to obtain a soil sample comprises: adding a plurality of mixing balls into the mixing barrel, the plurality of mixing balls comprising at least a first mixing ball and a second mixing ball, the first mixing ball and the second mixing ball having different masses; fixing the mixing barrel on a mixing machine to perform mixing to obtain a soil sample; wherein the mixing time is greater than 100 hours, and the mixing balls are stainless steel balls.

[0013] Preferably, an annular inner gasket is provided between the barrel cover and the barrel body of the mixing barrel, and the annular inner gasket is installed on the barrel cover of the mixing barrel.

[0014] Preferably, the first container is a beaker; wherein, drying the first soil matrix dripped with the radionuclide standard solution comprises: placing the beaker containing the first soil matrix in an oven for drying, wherein the first soil matrix in the beaker is dripped with the radionuclide standard solution, wherein the drying temperature of the oven is any value between 100°C and 110°C.

[0015] Preferably, the beaker is a polytetrafluoroethylene beaker.

[0016] Preferably, the first weight value ranges from 2500 g to 9000 g, and the second weight value ranges from 100 g to 500 g.

[0017] Preferably, before the soil matrix with the first weight value is weighed and placed in the mixing barrel, the method further includes: drying the soil in an oven at 105°C to constant weight, with the drying time being greater than or equal to 24 hours; grinding the dried soil in a ball mill; screening the ground soil to obtain the soil matrix; wherein stone balls are placed in the ball mill, the hardness value of the inner wall of the ball mill and the stone balls is greater than 50HRC, and the particle size of the soil matrix is ​​greater than or equal to 100 mesh.

[0018] The beneficial effects of the present disclosure are: using a soil sample preparation method for capability verification of radionuclide analysis provided by the present disclosure, preparing a first soil matrix and a second soil matrix for doping operation, the first soil matrix is ​​placed in a first container; dropping a radionuclide standard solution to a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container; drying the first soil matrix dripped with the radionuclide standard solution until the first soil matrix presents a loose fine powder; transferring the dried first soil matrix to a second container, and transferring the second soil matrix to the second container through the first container; mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample. The method provided by the present disclosure can make the radionuclide and the soil matrix mixed more evenly, and improve the uniformity of the capability verification sample. The present disclosure can also reduce the loss of the radionuclide standard solution in the soil sample preparation process, thereby improving the accuracy of the soil assessment of the verification sample. In addition, the present disclosure is dried and mixed in a sealed environment to prevent the sample from getting damp, thereby ensuring that the activity concentration value is not affected.

[0019] The soil samples prepared by the method provided in the present disclosure can effectively evaluate the determination capability of radionuclides in the soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0020] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0022] Figure 1 It is a schematic diagram of a process for preparing a soil sample according to an embodiment of the present disclosure.

[0023] Figure 2 It is a schematic diagram of a process for preparing a soil sample according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0025] It should be understood that the various steps described in the method embodiments of the present disclosure may be performed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present disclosure is not limited in this respect.

[0026] It should be noted that the concepts such as "first" and "second" mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0027] It should be noted that the modifications of "one" and "plurality" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0028] Example 1

[0029] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing soil samples for proficiency testing of radionuclide analysis, and the method includes the following S101 to S105.

[0030] S101, preparing a first soil matrix and a second soil matrix for a doping operation, wherein the first soil matrix is ​​placed in a first container.

[0031] S102, dripping a radionuclide standard solution into a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container.

[0032] S103, drying the first soil matrix dripped with the radionuclide standard solution until the first soil matrix is ​​in a loose fine powder state.

[0033] S104, transferring the dried first soil matrix to a second container, and transferring the second soil matrix to the second container through the first container.

[0034] S105, mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample.

[0035] The method provided by the present disclosure can make the radionuclide and soil matrix mix more evenly, and improve the uniformity of the proficiency verification sample. The present disclosure can also reduce the loss of radionuclide standard solution in the soil sample preparation process, thereby improving the accuracy of soil assessment of the verification sample. In addition, the present disclosure performs drying and mixing in a sealed environment to prevent the sample from being damp, thereby ensuring that the activity concentration value is not affected.

[0036] In one embodiment, before weighing the soil matrix of the first weight value and putting it into the mixing barrel, the method may further include: placing the soil in an oven at 105° C. and drying it to constant weight, with the drying time being greater than or equal to 24 hours; grinding the dried soil in a ball mill; screening the ground soil to obtain a soil matrix; wherein stone balls are placed in the ball mill, the hardness value of the inner wall of the ball mill and the stone balls is greater than 50HRC (Rockwell hardness C scale), and the particle size of the soil matrix is ​​greater than or equal to 100 mesh.

[0037] In the embodiment of the present disclosure, the soil may be natural soil, or the composition and properties of different soil matrices may be selected according to actual application requirements and application experience. For example, if the soil to be evaluated is a soil with a high alkalinity, correspondingly, the soil matrix for weighing the first weight value in the embodiment of the present disclosure is also a soil matrix with a high alkalinity.

[0038] It should be noted that soil matrix refers to the main components of solid matter in the soil, including mineral particles, organic matter, soil aggregates, etc. The nature and composition of the soil matrix have an important influence on the physical, chemical and biological properties of the soil.

[0039] In the disclosed embodiment, there is no limitation on the material of the inner wall and the stone balls of the ball mill, as long as the material has a hardness greater than 50HRC. For example, the material of the inner wall and the stone balls of the ball mill can be one or more of diamond, ceramic and some high alloy steel. For another example, the inner wall of the ball mill is made of diamond, and the material of the stone balls is ceramic. Placing the stone balls in the ball mill is conducive to improving the grinding efficiency, thereby increasing the preparation speed of the soil sample.

[0040] In the embodiments of the present disclosure, the drying time is not limited, as long as the soil matrix is ​​dried to a constant weight, and the meaning of constant weight is that the weight of the soil matrix does not change with the increase of the drying time. For example, the drying time is any time between 24 hours and 30 hours. For example, 25 hours.

[0041] In the disclosed embodiment, before the doping operation is performed, the soil is first dried to ensure the dryness of the soil matrix; the particle size of the soil matrix is ​​greater than or equal to 100 meshes, which is conducive to obtaining a uniformly mixed soil sample.

[0042] In another embodiment, the first container is a beaker, and the second container is a mixing barrel; wherein the first soil matrix and the second soil matrix prepared for the doping operation may include the following steps A1 and A2.

[0043] Step A1, weighing a soil matrix of a first weight value and putting it into a mixing bucket;

[0044] In the disclosed embodiment, the first weight value is determined according to the preparation needs. Exemplarily, in order to improve the assessment accuracy of the prepared soil sample, the first weight value is set to be greater than the theoretically required weight value, so that the loss of the soil matrix during the preparation process can be supplemented. For example, when the required first weight value is 8000g (gram), the soil matrix weighed in the disclosed embodiment is 8000.01g, wherein 0.01g is an additional increment. The value of the corresponding additional increment in the disclosed embodiment is not limited, and is determined according to the specific weight value lost in actual experience. Exemplarily, the first weight value is 8000.01 grams.

[0045] It should be noted that, in order to ensure the uniformity of the prepared soil sample, the first weight value is less than or equal to 30 kg, for example, the first weight value is less than or equal to 25 kg (kilograms), and exemplary, the first weight value is 5000.01 grams.

[0046] Exemplarily, the first weight value ranges from 2500 g to 9000 g.

[0047] In the disclosed embodiment, the granularity of the soil matrix is ​​greater than or equal to 100 meshes. For example, the granularity of the soil matrix is ​​any value among 120 meshes, 190 meshes, 200 meshes, 210 meshes, 220 meshes, 230 meshes, 240 meshes, 250 meshes, 260 meshes, 270 meshes, 280 meshes, 290 meshes, 300 meshes and 310 meshes. The granularity of the soil matrix of the disclosed embodiment is small enough to improve the adequacy of mixing, and then improve the reliability and evaluation accuracy of the verification sample. It should be noted that the size of the granularity will be different according to the different radionuclides analyzed.

[0048] Step A2, weigh out the first soil matrix of the second weight value from the mixing barrel and transfer it to a beaker, and take out the second soil matrix of the third weight value for later use, the first soil matrix and the second soil matrix are the same soil matrix.

[0049] In the disclosed embodiment, the second weight value and the third weight value are determined according to the preparation requirements. Exemplarily, the second weight value is any value between 100 grams and 500 grams, for example, the second weight value is 300 grams. The third weight value is any value between 500 grams and 5000 grams, for example, the third weight value is 1800 grams, 2000 grams, 2100 grams, 2400 grams, 2600 grams, 3000 grams, 4000 grams, 4500 grams and 5000 grams.

[0050] The second soil matrix is ​​used to clean the container containing the first soil matrix, thereby solving the problem of low assessment accuracy caused by the radionuclide standard solution contacting the container wall during the transfer process.

[0051] In yet another embodiment, the dried first soil matrix is ​​transferred to a second container, and the second soil matrix is ​​transferred to the second container through the first container.

[0052] In the disclosed embodiment, the second soil matrix is ​​transferred to the second container through the first container, which is equivalent to cleaning the first container with the second soil matrix. The number of cleanings is not limited, for example, the number of cleanings is any one of 5 to 10 times. For example, the first container is a beaker, and the number of cleanings of the beaker is 7 times. The disclosed embodiment can further reduce the loss of radionuclides by using a spare soil matrix (second soil matrix) to clean the beaker multiple times, thereby further improving the assessment accuracy.

[0053] The predetermined area is described below.

[0054] In one embodiment, dripping the radionuclide standard solution to a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container, may include at least one of the following:

[0055] Dropping the radionuclide standard solution onto the central area of ​​the surface of the first soil matrix contained in the first container, and the radionuclide standard solution does not contact the inner wall of the first container; or,

[0056] dripping the radionuclide standard solution into the geometric center area of ​​the first soil matrix contained in the first container, and the radionuclide standard solution does not contact the inner wall of the first container; or,

[0057] The radionuclide standard solution is dropped into the geometric center area of ​​the first container, and the radionuclide standard solution does not contact the inner wall of the first container.

[0058] In the disclosed embodiment, the radionuclide standard solution is a radioactive material solution of a specific concentration, and the radionuclides contained therein have known and stable concentrations and radioactive properties. It should be noted that the amount of the radionuclide standard solution added is determined according to the activity concentration level of the radionuclides in the prepared verification sample. For example, the radionuclide standard solution can be a Sr-90 (strontium-90) certified standard solution, and 10-1-101 mL of the radionuclide standard solution is added, wherein the Sr-90 certified standard solution refers to a certified solution containing a known concentration of Sr-90.

[0059] In the disclosed embodiment, the predetermined area can be a regular area, an irregular area, or a point. As long as the radionuclide standard solution dripped into the first soil matrix in the first container does not contact the first container. Exemplarily, the first container is a beaker, and the predetermined area is a point domain. The absorbed radionuclide standard solution is dripped into the middle of the beaker (point domain), which can ensure that the radionuclide standard solution will not diffuse to the wall of the beaker, and ensure that the added radionuclide standard solution is "all" in the first soil matrix, thereby reducing the loss of the radionuclide standard solution, thereby improving the assessment accuracy of the prepared soil sample. It should be noted that the regular area and the irregular area can be a plane area, or a three-dimensional area (such as a cylindrical area). For example, the radionuclide standard solution is dripped into the geometric center area of ​​the first soil matrix contained in the first container (such as the first soil matrix contained in the first container is cylindrical), and the shape of the area is spherical.

[0060] In the disclosed embodiment, the middle of the beaker may refer to the center of the soil matrix in the beaker, or may refer to the geometric center of the shape of the soil matrix in the beaker, which can effectively prevent the radioactive nuclide standard solution dropped into the beaker from diffusing to the wall of the beaker.

[0061] The beaker can be a polytetrafluoroethylene beaker, which has extremely high chemical resistance, is not easily corroded by acids, alkalis and organic solvents, is resistant to high temperatures, has excellent non-adhesive properties, and is easy to clean, thereby reducing the adhesion of the soil matrix to the beaker wall, which is beneficial to further improve the assessment accuracy of the prepared soil samples.

[0062] In another embodiment, dripping the radionuclide standard solution to a predetermined area of ​​the first soil matrix without the radionuclide standard solution contacting the inner wall of the first container may include: using a pipette to absorb the radionuclide standard solution, and dripping the radionuclide standard solution to a predetermined area of ​​the first soil matrix without the radionuclide standard solution contacting the inner wall of the first container.

[0063] In the disclosed embodiment, using a pipette with higher measurement accuracy to draw the radionuclide standard solution is beneficial to improving the assessment accuracy of the prepared soil sample.

[0064] The following describes how to mix and dry the samples.

[0065] In one embodiment, mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample may include: adding a plurality of mixing balls into a mixing barrel, the plurality of mixing balls including at least a first mixing ball and a second mixing ball, the first mixing ball and the second mixing ball having different masses; fixing the mixing barrel on a mixing machine to perform mixing to obtain a soil sample; wherein the mixing time is greater than 100 hours, and the mixing balls are stainless steel balls.

[0066] In the embodiment of the present disclosure, the number of sample mixing balls added is not limited. The more soil matrix there is in the sample mixing bucket, the more sample mixing balls are added. The masses of the multiple sample mixing balls are different, that is, the sizes of the sample mixing balls can be of various types, and the embodiment of the present disclosure is not limited to the first sample mixing ball and the second sample mixing ball.

[0067] In the disclosed embodiment, the mixing ball can be a stainless steel iron ball. The stainless steel iron ball is conducive to the rapid and uniform mixing of the soil matrix and the radioactive nuclides. It should be noted that the mixing ball can also be other spheres that can speed up the mixing speed. Furthermore, the material of the surface of the mixing ball can be an anti-adhesion material, which can further improve the assessment accuracy of the prepared soil sample.

[0068] In the disclosed embodiment, a proper amount of stainless steel balls of different sizes are added to the mixing barrel, and the movement of the balls in the mixing barrel can promote uniformity of the sample.

[0069] In the embodiment of the present disclosure, the time of the mixed sample treatment can be greater than or equal to 100 hours. Exemplarily, the time of the mixed sample treatment is any value between 95 hours and 105 hours. For example, the time of the mixed sample treatment is 105 hours. It should be noted that when the time of the mixed sample treatment is greater than 100 hours, the uniformity of the mixed sample is higher.

[0070] In another embodiment, an annular inner gasket is provided between the barrel cover and the barrel body of the mixing barrel, and the annular inner gasket is installed on the barrel cover of the mixing barrel. The mixing barrel is a mixing barrel with good sealing performance. The annular inner gasket on the mixing barrel can further ensure the sealing performance of the mixing barrel, thereby ensuring that the soil matrix and the radioactive nuclide mixture are well dried during a long mixing time, and further ensuring that the activity concentration value is not affected.

[0071] Exemplarily, the annular inner gasket may be an elastic annular inner gasket, which may further improve the sealing performance of the mixing barrel.

[0072] In another embodiment, the first container is a beaker; wherein, drying the first soil matrix dripped with the radionuclide standard solution may include: placing the beaker containing the first soil matrix in an oven for drying, wherein the first soil matrix in the beaker is dripped with the radionuclide standard solution, wherein the drying temperature of the oven is any value between 100°C and 110°C.

[0073] In the disclosed embodiment, for soil samples, humidity conditions need to be controlled to prevent moisture from changing the quality and thus affecting the activity concentration value. When the radionuclide standard solution is dripped into the first soil matrix for drying, the moisture can be reduced to ensure that the activity concentration value is not affected. It should be noted that the first soil matrix is ​​in a loose fine powder state, indicating that the first soil matrix is ​​fully dried and not damp (caked), which is conducive to subsequent mixing and accurate measurement.

[0074] In one embodiment, the drying temperature of the oven is any value between 100° C. and 110° C. For example, the drying temperature of the oven is 105° C. In the embodiment of the present disclosure, using a temperature of 105° C. to dry the first soil matrix to which the radionuclide standard solution is added generally does not affect the activity of the radionuclide, thereby ensuring that there is no adverse effect on the measurement result.

[0075] In the embodiment of the present disclosure, whether the drying is completed is determined by the state of drying the first soil matrix. For example, if the soil matrix is ​​dried to a loose fine powder state, it means that the drying is sufficient, which is conducive to subsequent mixing. In addition, the drying time (i.e., the time when the soil matrix is ​​dried to a loose fine powder state) can also be determined according to the size of the second weight value, that is, the time when the drying operation is completed.

[0076] The method provided by the present disclosure can make the radionuclide and soil mixed more uniformly, and improve the uniformity of the proficiency verification sample. The present disclosure can also reduce the loss of the radionuclide standard solution in the soil sample preparation process, thereby improving the accuracy of the soil assessment of the verification sample. In addition, the present disclosure uses an oven for drying operation and performs the mixed sample processing in a sealed environment to prevent the soil from being damp, thereby ensuring that the activity concentration value is not affected.

[0077] The soil samples prepared by the method provided in the present disclosure can effectively evaluate the determination capability of radionuclides in the soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0078] Example 2

[0079] like Figure 2 As shown, an embodiment of the present invention provides a method for preparing soil samples for proficiency testing of radionuclide analysis, and the method may include the following S101 and S106.

[0080] S101, preparing a first soil matrix and a second soil matrix for a doping operation, wherein the first soil matrix is ​​placed in a first container.

[0081] S102, dripping a radionuclide standard solution into a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container.

[0082] S103, drying the first soil matrix dripped with the radionuclide standard solution until the first soil matrix is ​​in a loose fine powder state.

[0083] S104, transferring the dried first soil matrix to a second container, and transferring the second soil matrix to the second container through the first container.

[0084] S105, mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample.

[0085] The above S101 to S105 have been explained in the above embodiment and will not be repeated here.

[0086] S106, performing a uniformity test on the soil sample, and if the test is passed, packaging the soil sample into plastic bottles to facilitate transportation and storage of the soil sample.

[0087] In the disclosed embodiment, the soil samples are packaged into plastic bottles and sealed for storage to prevent the soil samples from getting damp, thereby improving the accuracy of soil assessment of the verification samples.

[0088] Exemplarily, the proficiency testing soil sample is prepared by the method disclosed herein using a certified 137Cs standard solution and natural soil, and the prepared soil sample is divided into 500 mL plastic bottles, each bottle containing about 500 g, and sealed. The homogeneity of the proficiency testing soil sample is tested as follows.

[0089] 10 samples were randomly selected, and each sample was sampled separately and tested twice under repeated conditions. The uniformity test data is shown in Table 1. The unit of radioactive material activity is Bq / kg (Becq per kilogram), where the soil sample in each plastic bottle is one sample.

[0090] Table 1 Homogeneity test results of proficiency verification samples of γ-nuclides (137Cs) in soil

[0091]

[0092]

[0093] As can be seen from Table 1, the single-factor ANOVA method was used to obtain the statistic F = 1.44, F < F0.05 (9, 10) = 3.02, indicating that there was no significant difference within and between samples, and the samples were uniform. Using the Ss ≤ 0.3σ criterion (a criterion for judging process stability), Ss = 0.19, Ss ≤ 0.3σ = 0.26, the samples used were considered to be uniform in this capability verification. Among them, Ss is the standard deviation of the heterogeneity between samples.

[0094] It should be noted that for how to calculate relevant data between samples and within samples, please refer to CNAS-GL003:2018 "Guidelines for the Evaluation of Uniformity and Stability of Proficiency Testing Samples".

[0095] The method provided by the present disclosure can make the radionuclide and soil matrix mix more evenly, and improve the uniformity of the proficiency verification sample. The present disclosure can also reduce the loss of radionuclide standard solution in the soil sample preparation process, thereby improving the accuracy of soil assessment of the verification sample. In addition, the present disclosure performs drying and mixing in a sealed environment to prevent the sample from being damp, thereby ensuring that the activity concentration value is not affected.

[0096] The soil samples prepared by the method provided in the present disclosure can effectively evaluate the determination capability of radionuclides in the soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0097] Example 3

[0098] An embodiment of the present invention provides a method for preparing a soil sample for proficiency testing of radionuclide analysis. The method may include the following steps B1 to B7.

[0099] Step B1, weigh 8000.01 g of soil matrix and put it into a mixing bucket.

[0100] Step B2, take out 300 g of the first soil matrix from the mixing barrel and transfer it to a beaker, and take out 2100 g of the second soil matrix for use.

[0101] Step B3, use a pipette to draw 10 ml of the radionuclide standard solution, and drop the drawn radionuclide standard solution into the middle of the beaker to ensure that the radionuclide standard solution does not diffuse to the wall of the beaker.

[0102] Step B4, placing the beaker in an oven for drying at a temperature of 105° C. until the first soil matrix in the beaker is in a loose fine powder state.

[0103] Step B5, transfer the first soil matrix in the beaker to a sample mixing barrel, and use the spare second soil matrix to clean the beaker 7 times, and transfer the second soil matrix used for cleaning the beaker to the sample mixing barrel.

[0104] Step B6, add a plurality of mixing balls into the mixing barrel, the plurality of mixing balls at least including a first mixing ball and a second mixing ball, the first mixing ball and the second mixing ball have different masses, and the mixing ball can be a stainless steel iron ball. The mixing barrel is fixed on a mixing machine for mixing to obtain a soil sample. The mixing time is 105 hours.

[0105] Step B7, performing a uniformity test on the soil sample. If the test is passed, the soil sample is packaged into plastic bottles to facilitate transportation and storage of the soil sample.

[0106] The method provided by the present disclosure can make the radionuclide and soil matrix mix more evenly, and improve the uniformity of the proficiency verification sample. The present disclosure can also reduce the loss of radionuclide standard solution in the soil sample preparation process, thereby improving the accuracy of soil assessment of the verification sample. In addition, the present disclosure performs drying and mixing in a sealed environment to prevent the sample from being damp, thereby ensuring that the activity concentration value is not affected.

[0107] The soil samples prepared by the method provided in the present disclosure can effectively evaluate the determination capability of radionuclides in the soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0108] Example 4

[0109] An embodiment of the present invention provides a method for preparing soil samples for proficiency testing of radionuclide analysis. The method may include matrix preparation and preparation of spiked samples.

[0110] Matrix preparation: Natural soil is used as the soil matrix. It is placed in an oven at 105°C and dried for more than 24 hours to constant weight. After drying, it is ground in a ball mill. To avoid the infiltration of equipment materials during the grinding process, the lining and ball stones of the ball mill are made of materials with higher hardness. After grinding, it is sieved through a 100-mesh sieve and used when mixing samples.

[0111] Preparation of spiked samples: Use an electronic balance to accurately weigh a total of 3000.00 g of the first soil matrix into a mixing bucket. Transfer approximately 200 g of the first soil matrix to a polytetrafluoroethylene beaker, and separately set aside approximately 800 g of the second soil matrix for later use. Use a 5.00 mL pipette to pipette 5.00 mL of Sr-90 standard solution (22.13 Bq / mL, May 15, 2009), and carefully drip it into the middle of the polytetrafluoroethylene beaker (ensuring that the liquid does not spread to the beaker wall). Place the polytetrafluoroethylene beaker in an oven and dry it at 105 °C. At this time, the first soil matrix presents a loose fine powder. Transfer all of the first soil to the mixing bucket, and use the reserved second soil matrix to wash the beaker and the medicine spoon used for transfer at least 6 times, with special attention to washing the bottom of the beaker and the junction of the bottom and the cup wall, and then transfer all of it to the mixing bucket and start mixing multiple times for at least 100 hours. The mixing bucket has good airtightness, which can ensure that the sample is sealed and has good dryness during multiple mixing processes.

[0112] The prepared soil samples were subjected to homogeneity tests using the one-way analysis of variance method and the Ss≤0.3σ criterion. Randomly select 10 plastic bottles from the prepared soil samples, and conduct parallel tests on each sample according to the analysis method of "EJ / T 1035-2011" to obtain the strontium-90 activity concentration in the soil samples and calculate the statistic. Using the one-way analysis of variance method, the obtained statistic F = 1.22, F < F0.05(9,10) = 3.02, indicating that there is no significant difference within and between the samples, and the samples are homogeneous. Using the Ss≤0.3σ criterion, Ss = 0.77, Ss≤0.3σ = 1.23, and the prepared samples are considered to be homogeneous in this proficiency test and there is no significant difference.

[0113] The method provided by the present disclosure can make the mixing of radionuclides and soil matrix more uniform, improving the homogeneity of proficiency test samples. The present disclosure can also reduce the loss of radionuclide standard solution during the preparation of soil samples, thereby improving the accuracy of the verification samples for soil assessment. In addition, the present disclosure conducts drying and performs mixing treatment in a sealed environment to avoid moisture absorption of the samples, thereby ensuring that the activity concentration value is not affected.

[0114] The soil samples prepared by the method provided by the present disclosure can effectively evaluate the measurement ability of radionuclides in soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0115] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not disclosed in the present disclosure. The description and examples are to be regarded as exemplary only, and the true scope of the present disclosure is indicated by the appended claims.

Claims

1. A method for preparing soil samples for proficiency testing of radionuclide analysis, characterized in that: The method comprises the following steps: S101, preparing a first soil matrix and a second soil matrix for a doping operation, wherein the first soil matrix is ​​placed in a first container; S102, dropping a radionuclide standard solution onto a predetermined area of ​​the first soil matrix, wherein the radionuclide standard solution does not contact an inner wall of the first container; S103, drying the first soil matrix dripped with the radionuclide standard solution until the first soil matrix is ​​in a loose fine powder state; S104, transferring the dried first soil matrix to a second container, and transferring the second soil matrix to the second container through the first container; S105, mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample.

2. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 1, characterized in that: Step S102 includes at least one of the following: Dropping a radionuclide standard solution onto a central area of ​​a surface of a first soil matrix contained in a first container, wherein the radionuclide standard solution does not contact an inner wall of the first container; or, Dropping a radionuclide standard solution into a geometric center area of ​​a first soil matrix contained in a first container, wherein the radionuclide standard solution does not contact an inner wall of the first container; or, The radionuclide standard solution is dropped into the geometric center area of ​​the first container, and the radionuclide standard solution does not contact the inner wall of the first container.

3. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 1, characterized in that: Step S102 includes: The radionuclide standard solution is sucked by a pipette and dropped onto a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not contact the inner wall of the first container.

4. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 1, characterized in that: The first container is a beaker, and the second container is a sample mixing barrel; The first soil matrix and the second soil matrix to be subjected to the standard addition operation include: Weigh a soil matrix of a first weight value and put it into the sample mixing bucket; The first soil matrix with a second weight value is weighed out from the mixing barrel and transferred to the beaker, and the second soil matrix with a third weight value is taken out for later use, wherein the first soil matrix and the second soil matrix are the same soil matrix.

5. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 4, characterized in that: Step S105 also includes: Adding a plurality of sample mixing balls into the sample mixing barrel, wherein the plurality of sample mixing balls include at least a first sample mixing ball and a second sample mixing ball, and the first sample mixing ball and the second sample mixing ball have different masses; The sample mixing barrel is fixed on a sample mixing machine to perform sample mixing to obtain a soil sample; The mixing time is greater than 100 hours, and the mixing balls are stainless steel balls.

6. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 4 or 5, characterized in that: An annular inner gasket is provided between the barrel cover and the barrel body of the sample mixing barrel, and the annular inner gasket is installed on the barrel cover of the sample mixing barrel.

7. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 1, characterized in that: The first container is a beaker; The step of drying the first soil matrix dripped with the radionuclide standard solution comprises: The beaker containing the first soil matrix is ​​placed in an oven for drying, wherein the first soil matrix in the beaker is dripped with the radionuclide standard solution, wherein the drying temperature of the oven is any value between 100° C. and 110° C.

8. The method for preparing soil samples for proficiency testing of radionuclide analysis according to any one of claims 4, 5 and 7, characterized in that: The beaker is a polytetrafluoroethylene beaker.

9. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 4, characterized in that: The first weight value ranges from 2500 grams to 9000 grams, and the second weight value ranges from 100 grams to 500 grams.

10. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 4, characterized in that: Before the soil matrix with the first weight value is weighed and placed in the sample mixing bucket, the method further comprises: Place the soil in an oven at 105°C and dry it to constant weight for 24 hours or more; Grind the dried soil in a ball mill; Screening the ground soil to obtain the soil matrix; Wherein, stone balls are placed in the ball mill, the hardness value of the inner wall of the ball mill and the stone balls is greater than 50HRC, and the particle size of the soil matrix is ​​greater than or equal to 100 meshes.

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