A method for the preparation of proficiency testing soil samples for radionuclide analysis

Abstract

The present application relates to a kind of for radionuclide analysis proficiency testing soil sample preparation method.Belong to the technical field of radiation environment monitoring, first soil matrix and second soil matrix are prepared to be mixed with standard operation, first soil matrix is contained in first container;Radioactive standard solution is dropped to the predetermined area of first soil matrix, and radioactive standard solution does not contact with the inner wall of first container;First soil matrix with radioactive standard solution is dropped is dried, until first soil matrix presents loose fine powder;First soil matrix after drying is transferred to second container, and second soil matrix is transferred to second container by first container;First soil matrix and second soil matrix in second container are mixed, and soil sample is obtained.The method provided in the present application can make radionuclide and soil more uniform, improve the uniformity of proficiency testing sample.

Description

Technical Field

[0001] This invention relates to the field of radiation environment monitoring technology, and in particular to a method for preparing soil samples for proficiency testing of radionuclide analysis. Background Technology

[0002] With the widespread application of nuclear energy technology and increasing concern over nuclear waste disposal, monitoring radionuclides in soil has become particularly important. Soil, as a crucial component of the ecosystem, directly impacts crop growth, environmental quality, and human health. Therefore, monitoring radionuclides in soil not only helps assess the environmental impact of nuclear contamination but also safeguards food safety and public health.

[0003] Radionuclides in soil may originate from natural local radiation, nuclear testing, nuclear accidents, or waste disposal. Long-term exposure to high doses of radioactive materials can cause radiation damage to organisms, leading to various health problems, including cancer and hereditary diseases. Therefore, monitoring radionuclides in soil helps in the timely detection and assessment of environmental pollution, enabling the implementation of appropriate protective measures and reducing the risks of radiation to the ecosystem and human health.

[0004] Due to the scarcity of radionuclide standard materials in soil, the analysis of radionuclides in soil samples often employs the doping method for preparation during internal laboratory quality control, interlaboratory comparisons, and proficiency testing. However, since some radionuclides lack solid-type standard materials, the following problems arise when mixing radionuclide standard solutions with soil samples:

[0005] The standard-addition method is used to prepare proficiency testing samples (soil samples) for evaluating the laboratory's ability to analyze radionuclides in soil. However, this method suffers from low homogeneity because it cannot guarantee uniform mixing of the soil and radionuclide solution. Furthermore, during soil sample preparation, there is a risk of radionuclide solution loss through the container walls, affecting the accuracy of the evaluation. Additionally, soil is susceptible to moisture, which can easily affect the activity concentration of radionuclides in the soil sample. Therefore, this application provides a method for preparing proficiency testing soil samples for radionuclide analysis.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

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

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing soil samples for proficiency testing of radionuclide analysis, comprising the following steps: preparing a first soil matrix and a second soil matrix for standard doping, wherein the first soil matrix is ​​placed in a first container; dripping a radionuclide standard solution onto a predetermined area of ​​the first soil matrix, wherein the radionuclide standard solution does not contact the inner wall of the first container; drying the first soil matrix with the radionuclide standard solution dripped onto it until the first soil matrix appears as a loose fine powder; transferring the dried first soil matrix to a second container, and transferring the second soil matrix through the first container to the second container; and mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample.

[0009] Preferably, the radionuclide standard solution is 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, including at least one of the following: 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, dropping the radionuclide standard solution onto 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, dropping the radionuclide standard solution onto 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 onto a predetermined area of ​​the first soil matrix, wherein the radionuclide standard solution does not contact the inner wall of the first container, comprises: using a pipette to draw the radionuclide standard solution and dripping the radionuclide standard solution onto the predetermined area of ​​the first soil matrix, wherein the radionuclide standard solution does not contact the inner wall of the first container.

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

[0012] Preferably, the step of mixing the first soil matrix and the second soil matrix in the second container to obtain a soil sample includes: adding a plurality of mixing balls to the mixing bucket, 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 bucket on a mixing machine to perform the mixing process 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 pad is provided between the lid and the body of the mixing container, and the annular inner pad is installed on the lid of the mixing container.

[0014] Preferably, the first container is a beaker; wherein, drying the first soil substrate containing the radionuclide standard solution includes: placing the beaker containing the first soil substrate in an oven for drying, wherein the first soil substrate in the beaker contains the radionuclide standard solution, wherein the drying temperature of the oven is any value between 100℃ and 110℃.

[0015] Preferably, the beaker is a polytetrafluoroethylene (PTFE) beaker.

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

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

[0018] The beneficial effects of this disclosure are as follows: Using the proficiency testing soil sample preparation method for radionuclide analysis provided in this disclosure, a first soil matrix and a second soil matrix are prepared for standard doping. The first soil matrix is ​​placed in a first container. A radionuclide standard solution is dropped onto a predetermined area of ​​the first soil matrix, ensuring that the radionuclide standard solution does not contact the inner wall of the first container. The first soil matrix with the dropped radionuclide standard solution is dried until it becomes a loose, fine powder. The dried first soil matrix is ​​transferred to a second container, and the second soil matrix is ​​transferred from the first container to the second container. The first and second soil matrices in the second container are mixed to obtain a soil sample. The method provided in this disclosure enables more uniform mixing of radionuclides and soil matrix, improving the homogeneity of the proficiency testing sample. This disclosure also reduces the loss of radionuclide standard solution during soil sample preparation, thereby improving the accuracy of the verification sample in assessing the soil. Furthermore, this disclosure involves drying and mixing in a sealed environment to prevent the sample from becoming damp, thus ensuring that the activity concentration value is not affected.

[0019] The method provided in this disclosure enables the preparation of soil samples that effectively assess the ability to detect radionuclides in soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0022] Figure 1 This is a schematic flowchart of a method for preparing a soil sample according to an embodiment of the present disclosure.

[0023] Figure 2 This is a schematic flowchart of a method for preparing a soil sample according to another embodiment of this disclosure. Detailed Implementation

[0024] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary 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 steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

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

[0027] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0028] Example 1

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

[0030] S101, the first soil matrix and the second soil matrix are prepared for the standard mixing operation, and the first soil matrix is ​​placed in the first container.

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

[0032] S103, the first soil matrix containing the radioactive nuclide standard solution is dried until the first soil matrix appears as a loose fine powder.

[0033] S104, the dried first soil substrate is transferred to the second container, and the second soil substrate is transferred from the first container to the second container.

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

[0035] The method provided in this disclosure enables more uniform mixing of radionuclides with the soil matrix, improving the homogeneity of proficiency testing samples. This disclosure also reduces the loss of radionuclide standard solutions during soil sample preparation, thereby improving the accuracy of soil assessment using the testing samples. Furthermore, this disclosure includes drying and mixing in a sealed environment to prevent sample moisture absorption, thus ensuring that the activity concentration values ​​remain unaffected.

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

[0037] In this embodiment of the disclosure, the soil can be natural soil, or the composition and properties of different soil substrates can be selected according to actual application needs and application experience. For example, if the soil being evaluated is a soil with high alkalinity, correspondingly, the soil substrate for which the first weight value is weighed in this embodiment of the disclosure is also a soil substrate with high alkalinity.

[0038] It should be noted that soil matrix refers to the main solid components of soil, including mineral particles, organic matter, and soil aggregates. The properties and composition of the soil matrix have a significant impact on the physical, chemical, and biological characteristics of soil.

[0039] In this embodiment, the materials of the inner wall of the ball mill and the stone balls are not limited; any material with a hardness greater than 50 HRC is acceptable. For example, the inner wall of the ball mill and the stone balls can be made of one or more of diamond, ceramic, and some high-alloy steels. As another example, the inner wall of the ball mill can be made of diamond, and the stone balls can be made of ceramic. Placing the stone balls inside the ball mill helps to improve grinding efficiency, thereby increasing the preparation speed of soil samples.

[0040] In this embodiment, the drying time is not limited, as long as the soil substrate is dried to a constant weight. Constant weight means that the weight of the soil substrate does not change with increasing drying time. For example, the drying time can be any time between 24 and 30 hours, such as 25 hours.

[0041] In this embodiment of the disclosure, the soil is dried before the standard admixture operation to ensure the dryness of the soil matrix; a soil matrix particle size greater than or equal to 100 mesh is beneficial to obtaining a uniformly mixed soil sample.

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

[0043] Step A1: Weigh the first weight value of soil matrix and put it into the mixing container;

[0044] In this embodiment of the disclosure, the first weight value is determined according to the preparation requirements. For example, to improve the evaluation accuracy of the prepared soil sample, the first weight value is set to be greater than the theoretically required weight value, thus compensating for losses of the soil matrix during the preparation process. For instance, when the required first weight value is 8000g, the soil matrix weighed in this embodiment is 8000.01g, where 0.01g is an additional increment. The value of this additional increment is not limited in this embodiment and is determined based on the specific weight loss observed in practical experience. For example, the first weight value is 8000.01g.

[0045] It should be noted that, in order to ensure the homogeneity of the prepared soil samples, 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, and exemplarily, the first weight value is 5000.01 g.

[0046] For example, the first weight value ranges from 2500 grams to 9000 grams.

[0047] In this embodiment of the disclosure, the particle size of the soil matrix is ​​greater than or equal to 100 mesh. For example, the particle size of the soil matrix is ​​any value among 120 mesh, 190 mesh, 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh, 250 mesh, 260 mesh, 270 mesh, 280 mesh, 290 mesh, 300 mesh, and 310 mesh. The sufficiently small particle size of the soil matrix in this embodiment of the disclosure can improve the thoroughness of mixing, thereby improving the reliability and evaluation accuracy of the verification sample. It should be noted that the particle size may vary depending on the radionuclide being analyzed.

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

[0049] In this embodiment of the disclosure, the second and third weight values ​​are determined according to the preparation requirements. For example, the second weight value is any value between 100g and 500g, such as 300g. The third weight value is any value between 500g and 5000g, such as 1800g, 2000g, 2100g, 2400g, 2600g, 3000g, 4000g, 4500g, and 5000g.

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

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

[0052] In this embodiment, the second soil matrix is ​​transferred from the first container to the second container, which is equivalent to cleaning the first container with the second soil matrix. The number of cleaning cycles is not limited; for example, it can be any number of cycles between 5 and 10. For instance, if the first container is a beaker, the beaker is cleaned 7 times. By using a spare soil matrix (the second soil matrix) to clean the beaker multiple times, this embodiment can further reduce the loss of radionuclides and thus further improve the accuracy of the assessment.

[0053] The following is an explanation of the designated area.

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

[0055] A radionuclide standard solution is dropped onto the center area of ​​the surface of a first soil matrix contained in a first container, ensuring that the radionuclide standard solution does not contact the inner wall of the first container; or,

[0056] A radionuclide standard solution is dropped onto the geometric center of a first soil matrix contained in a first container, ensuring that the radionuclide standard solution does not contact the inner wall of the first container; or,

[0057] A radioactive nuclide standard solution is dropped onto the geometric center region of the first container, without the radioactive nuclide standard solution coming into contact with the inner wall of the first container.

[0058] In this embodiment, the radionuclide standard solution is a radioactive material solution of a specific concentration, containing radionuclides with known and stable concentrations and radioactive properties. It should be noted that the amount of radionuclide standard solution added is determined based on the activity concentration level of the radionuclide in the prepared verification sample. For example, the radionuclide standard solution can be a certified Sr-90 (Sr-90) standard solution, with 10⁻¹⁰¹ mL added. Here, the certified Sr-90 standard solution refers to a certified solution containing a known concentration of Sr-90.

[0059] In this embodiment, the predetermined region can be a regular region, an irregular region, or even a point. The key is to ensure that the radionuclide standard solution dropped into the first soil matrix within the first container does not come into contact with the first container. For example, the first container is a beaker, and the predetermined region is a point region. Dropping the absorbed radionuclide standard solution to the center of the beaker (the point region) ensures that the radionuclide standard solution does not diffuse to the beaker wall, guaranteeing that the added radionuclide standard solution is "entirely" within the first soil matrix. This reduces the loss of the radionuclide standard solution and improves the evaluation accuracy of the prepared soil sample. It should be noted that the regular and irregular regions can be planar or three-dimensional (e.g., cylindrical). For instance, dropping the radionuclide standard solution into the geometric center of the first soil matrix (e.g., the first soil matrix in the first container is cylindrical) results in a spherical shape.

[0060] In this embodiment of the disclosure, the middle part of the beaker can refer to the center of the soil matrix inside the beaker, or it can refer to the geometric center of the shape of the soil matrix inside the beaker, which can effectively prevent the radioactive nuclide standard solution dripped into the beaker from diffusing to the beaker wall.

[0061] The beaker can be made of polytetrafluoroethylene (PTFE), which has extremely high chemical resistance, is not easily corroded by acids, alkalis and organic solvents, is heat resistant, and has excellent non-adhesive properties, making it easy to clean. This can reduce the adhesion of soil matrix to the beaker wall, which is beneficial to further improve the evaluation accuracy of the prepared soil samples.

[0062] In another embodiment, dropping a radionuclide standard solution onto a predetermined area of ​​a first soil matrix, wherein the radionuclide standard solution does not contact the inner wall of the first container, may include: using a pipette to draw the radionuclide standard solution and dropping it onto a predetermined area of ​​the first soil matrix, wherein the radionuclide standard solution does not contact the inner wall of the first container.

[0063] In this embodiment of the disclosure, using a pipette with high measurement accuracy to draw up the radionuclide standard solution is beneficial to improving the evaluation accuracy of the prepared soil sample.

[0064] The following explains how to mix and dry 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 to a mixing bucket, 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 bucket 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 this embodiment of the disclosure, the number of mixing balls added is not limited. The more soil matrix in the mixing container, the more mixing balls are added. The multiple mixing balls have different masses, meaning they can be of various sizes; this embodiment is not limited to only two types: first mixing balls and second mixing balls.

[0067] In this embodiment, the mixing ball can be a stainless steel ball. Stainless steel balls facilitate rapid and uniform mixing of the soil matrix and radionuclides. It should be noted that the mixing ball can also be other spheres that can accelerate the mixing process. Furthermore, the surface material of the mixing ball can be an anti-sticking material, which can further improve the evaluation accuracy of the prepared soil samples.

[0068] In this embodiment of the present disclosure, an appropriate amount of stainless steel balls of different sizes are added to the mixing tank. The movement of the balls in the mixing tank can promote sample homogenization.

[0069] In this embodiment of the disclosure, the mixing time can be greater than or equal to 100 hours. For example, the mixing time can be any value between 95 and 105 hours. For instance, the mixing time is 105 hours. It should be noted that a mixing time greater than 100 hours results in higher uniformity of the mixture.

[0070] In another embodiment, an annular inner gasket is provided between the lid and the body of the mixing container, and the annular inner gasket is installed on the lid of the mixing container. The mixing container is a well-sealed mixing container. The annular inner gasket on the mixing container can further ensure the sealing of the mixing container, thereby ensuring that the soil matrix and radionuclide mixture remains well dried during a long mixing time, and further ensuring that the activity concentration value is not affected.

[0071] For example, the annular inner pad can be an elastic annular inner pad, which can further improve the sealing of the mixing container.

[0072] In another embodiment, the first container is a beaker; wherein drying the first soil matrix containing 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 contains the radionuclide standard solution, wherein the drying temperature of the oven is any value between 100°C and 110°C.

[0073] In this embodiment, humidity conditions need to be controlled for soil samples to prevent changes in quality due to moisture, which could affect the activity concentration value. Adding the radionuclide standard solution dropwise to the first soil matrix and then drying it reduces moisture, ensuring the activity concentration value remains unaffected. It should be noted that the first soil matrix is ​​a loose, fine powder, indicating that it is fully dried and not damp (clumped), which facilitates subsequent mixing and ensures 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 this embodiment of the disclosure, using a temperature of 105°C to dry the first soil matrix containing the radionuclide standard solution generally does not affect the activity of the radionuclide, thus ensuring that it does not adversely affect the measurement results.

[0075] In this embodiment of the disclosure, the drying completion is determined by the state of the first soil substrate after drying. For example, drying until the soil substrate is in a loose, fine powder state indicates that it is sufficiently dried, which is beneficial for subsequent mixing. In addition, the drying time (i.e., the time until the soil substrate is in a loose, fine powder state) can also be determined based on the magnitude of the second weight value, that is, the time when the drying operation ends.

[0076] The method provided in this disclosure enables more uniform mixing of radionuclides with soil, improving the homogeneity of proficiency testing samples. This disclosure also reduces the loss of radionuclide standard solutions during soil sample preparation, thereby improving the accuracy of soil assessment using the testing samples. Furthermore, this disclosure employs an oven drying process and performs mixing in a sealed environment to prevent soil moisture absorption, thus ensuring that the activity concentration values ​​remain unaffected.

[0077] The method provided in this disclosure enables the preparation of soil samples that effectively assess the ability to detect radionuclides in soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0078] Example 2

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

[0080] S101, the first soil matrix and the second soil matrix are prepared for the standard mixing operation, and the first soil matrix is ​​placed in the first container.

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

[0082] S103, the first soil matrix containing the radioactive nuclide standard solution is dried until the first soil matrix appears as a loose fine powder.

[0083] S104, the dried first soil substrate is transferred to the second container, and the second soil substrate is transferred from the first container to the second container.

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

[0085] S101 to S105 have been described in the above embodiments and will not be repeated here.

[0086] S106, the uniformity of the soil sample is tested. If the test is passed, the soil sample is packaged into plastic bottles for easy transportation and storage.

[0087] In this embodiment of the disclosure, soil samples are aliquoted into sealed plastic bottles to prevent them from getting damp, thereby improving the accuracy of soil assessment using the verified samples.

[0088] For example, proficiency testing soil samples are prepared using a certified 137Cs standard solution and natural soil according to the method of this disclosure. The prepared soil samples are aliquoted into 500mL plastic bottles, each containing approximately 500g, and sealed. The homogeneity of the proficiency testing soil samples is tested as follows.

[0089] Ten samples were randomly selected, and each sample was taken separately and tested twice under repeated conditions. The homogeneity test data are shown in Table 1. The unit of radioactivity activity is Bq / kg (becq per kilogram). The soil sample in each plastic bottle is considered as one sample.

[0090] Table 1. Results of homogeneity test of γ-nucleoside (137Cs) samples in soil for proficiency testing

[0091]

[0092]

[0093] As shown in Table 1, the one-way ANOVA yielded a statistic F = 1.44, where F < F0.05(9,10) = 3.02, indicating no significant differences within or between samples, suggesting the samples are homogeneous. Using the Ss ≤ 0.3σ criterion (a criterion for assessing process stability), Ss = 0.19, and Ss ≤ 0.3σ = 0.26, the samples used were considered homogeneous in this proficiency testing. Here, Ss represents the standard deviation of heterogeneity between samples.

[0094] It should be noted that for information on how to calculate relevant data between and within samples, please refer to CNAS-GL003:2018 "Guidelines for evaluating the homogeneity and stability of proficiency testing samples".

[0095] The method provided in this disclosure enables more uniform mixing of radionuclides with the soil matrix, improving the homogeneity of proficiency testing samples. This disclosure also reduces the loss of radionuclide standard solutions during soil sample preparation, thereby improving the accuracy of soil assessment using the testing samples. Furthermore, this disclosure includes drying and mixing in a sealed environment to prevent sample moisture absorption, thus ensuring that the activity concentration values ​​remain unaffected.

[0096] The method provided in this disclosure enables the preparation of soil samples that effectively assess the ability to detect radionuclides in soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0097] Example 3

[0098] The present invention provides a method for preparing soil samples for proficiency testing of radionuclide analysis, the method including the following steps B1 to B7.

[0099] Step B1: Weigh 8000.01g of soil substrate and put it into the mixing bucket.

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

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

[0102] Step B4: Place the beaker in an oven to dry at a temperature of 105°C until the first soil matrix inside the beaker becomes a loose, fine powder.

[0103] Step B5: Transfer the first soil matrix in the beaker to the mixing container, and wash the beaker 7 times with the prepared second soil matrix. Then transfer the second soil matrix used to wash the beaker to the mixing container.

[0104] Step B6: Add multiple mixing balls to the mixing container. These balls include at least a first mixing ball and a second mixing ball, and the first and second mixing balls have different masses. The mixing balls can be stainless steel or iron balls. Fix the mixing container onto the mixing machine for mixing to obtain a soil sample. The mixing process takes 105 hours.

[0105] Step B7: Conduct a homogeneity test on the soil sample. If the test is passed, the soil sample is packaged into plastic bottles for easy transportation and storage.

[0106] The method provided in this disclosure enables more uniform mixing of radionuclides with the soil matrix, improving the homogeneity of proficiency testing samples. This disclosure also reduces the loss of radionuclide standard solutions during soil sample preparation, thereby improving the accuracy of soil assessment using the testing samples. Furthermore, this disclosure includes drying and mixing in a sealed environment to prevent sample moisture absorption, thus ensuring that the activity concentration values ​​remain unaffected.

[0107] The method provided in this disclosure enables the preparation of soil samples that effectively assess the ability to detect radionuclides in soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0108] Example 4

[0109] This invention provides a method for preparing soil samples for proficiency testing of radionuclide analysis, which may include matrix preparation and preparation of standard-admixed samples.

[0110] Matrix preparation: Natural soil was used as the soil matrix and dried in an oven at 105℃ for at least 24 hours until constant weight was achieved. After drying, it was ground in a ball mill. To prevent the penetration of equipment materials during the grinding process, the lining and grinding balls of the ball mill were made of a high-hardness material. After grinding, it was passed through a 100-mesh sieve and used for sample mixing.

[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 additionally take out approximately 800 g of the second soil matrix for standby; 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 (ensure that the liquid does not spread to the beaker wall). Place the polytetrafluoroethylene beaker in an oven at 105 °C to dry. 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 standby 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 beaker wall, and then transfer all of them 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 testing 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 without significant differences.

[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 sample moisture absorption, 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 determination ability of radionuclides in soil, thereby improving the overall monitoring level and ensuring environmental protection and public safety.

[0115] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this 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 includes the following steps: S101. Prepare a first soil matrix and a second soil matrix for the standard mixing operation, wherein the first soil matrix is ​​placed in a first container; S102. A radionuclide standard solution is dropped onto a predetermined area of ​​the first soil matrix, and the radionuclide standard solution does not come into contact with the inner wall of the first container. S103. Dry the first soil matrix containing the radionuclide standard solution until the first soil matrix appears as a loose fine powder. S104. Transfer the dried first soil matrix to the second container, and transfer the second soil matrix from the first container to the second container; S105. The first soil matrix and the second soil matrix in the second container are mixed 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: A radionuclide standard solution is dropped onto the central area of ​​the surface of the first soil matrix contained in the first container, and the radionuclide standard solution does not come into contact with the inner wall of the first container. or, A radionuclide standard solution is dropped onto the geometric center region of a first soil matrix contained in a first container, and the radionuclide standard solution does not come into contact with the inner wall of the first container. or, A radionuclide standard solution is dropped onto the geometric center region of the first container, and the radionuclide standard solution does not come into contact with 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 drawn up using a pipette and dropped onto a predetermined area of ​​the first soil matrix, ensuring that the radionuclide standard solution does not come into contact with 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 mixing tank; The first and second soil substrates prepared for the standard admixture operation include: Weigh out the first weight value of the soil matrix and place it into the mixing container; The second weight value of the first soil matrix is ​​weighed from the mixing container and transferred to the beaker, and the third weight value of the second soil matrix is ​​taken out for later use. 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: Add a plurality of mixing balls to the mixing container, 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; The mixing bucket is fixed on the mixing machine for mixing to obtain a soil sample; The mixing time is greater than 100 hours, and the mixing ball is a stainless steel ball.

6. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 4 or 5, characterized in that, The mixing container has an annular inner pad between the lid and the body, and the annular inner pad is installed on the lid of the mixing container.

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 containing the radionuclide standard solution includes: A beaker containing a first soil matrix is ​​placed in an oven to dry. The first soil matrix in the beaker is dripped with the radionuclide standard solution. The drying temperature of the oven is any value between 100℃ and 110℃.

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 2500g to 9000g, and the second weight value ranges from 100g to 500g.

10. The method for preparing soil samples for proficiency testing of radionuclide analysis according to claim 4, characterized in that, Before the soil matrix of the first weight value is placed into the mixing container, the method further includes: The soil was placed in an oven and dried at 105°C until constant weight, with a drying time of 24 hours or more. The dried soil was ground in a ball mill. The ground soil was screened to obtain the soil matrix; The ball mill contains stone balls, the inner wall of the ball mill and the stone balls have a hardness value greater than 50 HRC, and the soil matrix has a particle size greater than or equal to 100 mesh.

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