A method for measuring the particle size distribution of gamma nuclides

Abstract

The present application relates to the technical field of radiation monitoring, and discloses a kind of particle size distribution measurement methods of γ radionuclide, comprising: the measurement of initial sample: the radioactive nuclide sample adsorbed on the wall of sample container and the radioactive nuclide sample remaining on the wall of sample container are measured, after measurement is completed, sample is subsequently separated;Blank sample measurement: multiple pieces of filter membrane of each aperture are randomly selected, the filter membrane is made into specified geometric shape, and is measured in high-purity germanium gamma spectrometer;Radionuclide particle size separation: according to the measurement result of initial sample, the measurement result of one of the highest radioactivity concentration is sorted from low to high, and is sequentially separated;Radionuclide particle size measurement: the filter membrane of the same group and the same particle size is placed on the surface dish and numbered, and is measured after being dried to constant weight in the oven, the present application can grasp the particle size distribution and activity concentration of different nuclides in liquid effluent.

Description

Technical Field

[0001] This invention relates to the field of radiation monitoring technology, and in particular to a method for measuring the particle size distribution of γ nuclides. Background Technology

[0002] In recent years, with the increasing awareness of environmental protection in my country, the public's concern about the environmental impact of nuclear facility operations has also grown, leading to further requirements for the discharge of radioactive effluents from nuclear facilities. Liquid effluents from nuclear power plants contain fission and activation products with a certain level of activity. Before being discharged into the environment, they must undergo multi-stage purification and filtration equipment within the plant. Discharge is only permitted after monitoring confirms that the specific activity of each radionuclide meets regulatory requirements. Therefore, the effectiveness of purification and filtration equipment is crucial, and the particle size distribution of radionuclides in the liquid effluent affects the filtration efficiency and lifespan of the filters. Conducting relevant particle size distribution studies can provide support for the selection of upstream and downstream purification equipment and process optimization, and also provide a theoretical foundation for in-depth research on the changes in the physicochemical forms of radionuclides during their generation and migration in nuclear power plants.

[0003] Currently, there is limited domestic research on the particle size distribution of radionuclides in liquid effluents from nuclear power plants. Limited international research suggests that radionuclides exist in liquid effluents not as ions, but rather as clusters or particles, and that the particle size of the radionuclides' carriers may be related to their activity concentration. Establishing methods for measuring the particle size distribution in liquid effluents from nuclear power plants and their upstream influent is crucial for a deeper understanding of the physicochemical properties of radionuclides in these effluents. Summary of the Invention

[0004] To address the aforementioned technical problems, this disclosure provides a method for measuring the particle size distribution of γ-nuclides, which can determine the particle size distribution and activity concentration of different nuclides in liquid effluents.

[0005] This disclosure provides a method for measuring the particle size distribution of γ-nuclides, including:

[0006] Initial sample measurement: After adding distilled water to the radionuclide sample adsorbed on the sample container wall and stirring it evenly, a certain volume was measured, weighed, and then placed into a sample bottle. The sample was then placed in a high-purity germanium gamma spectrometer for measurement. After the measurement was completed, the sample was poured back into the corresponding beaker for subsequent separation.

[0007] Measurement of blank samples: Randomly select multiple filter membranes of each pore size, fabricate the filter membranes into the specified geometric shape, and place them in a high-purity germanium gamma spectrometer for 24 hours for measurement;

[0008] Separation of radioactive nuclide particle size: Based on the measurement results of the initial sample, the nuclide with the highest radioactivity concentration is sorted from low to high and separated sequentially. Each sample is then separated sequentially according to the filter membrane pore size from large to small, and the filter membrane is replaced during the filtration process according to the separation results.

[0009] Measurement of radionuclide particle size: Place filter membranes of the same particle size in the same group on a petri dish and number them. Dry them in an oven until constant weight and then measure them. After filtration, shake the filtrate well and measure a certain volume into a sample bottle for measurement.

[0010] Optionally, the radionuclide sample adsorbed on the wall of the sample container can be shaken off, transferred to a beaker, rinsed with distilled water, and then transferred to the beaker and stirred evenly.

[0011] Optionally, a high-frequency ultrasonic oscillation method can be used to vibrate and remove the radionuclides adsorbed on the container wall. The frequency of the high-frequency ultrasonic cleaner is 60kHz and the oscillation time is 6h.

[0012] Optionally, the energy resolution (FWHM) of the high-purity germanium gamma spectrometer is less than 2.0 keV (60Co, 1332.5 keV).

[0013] Optionally, the filter membrane can be fabricated into a specified geometry using a pressing machine with a pressure of 10 tons or more.

[0014] Optionally, the shape and size of the filter membrane can be the same as those of the efficiency calibration standard source.

[0015] Optionally, the filter membrane can be made of polypropylene.

[0016] Optionally, the pressure during the filtration process is constant at 0.07 MPa.

[0017] Optionally, to avoid the influence of changes in the pore size of the filter membrane during the filtration process, the filtration time for every 50 mL of sample is recorded. If the change exceeds 3 seconds, the filter membrane is replaced; otherwise, the filter membrane is replaced every 5 minutes.

[0018] Optionally, the drying temperature is 60°C.

[0019] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0020] This disclosure provides a method for measuring the particle size distribution of gamma nuclides. First, a certain volume of the radionuclide sample adsorbed on the sample container wall is mixed with distilled water, weighed, and placed into a sample bottle. The sample is then placed in a high-purity germanium gamma spectrometer for measurement. After measurement, the sample is returned to the corresponding beaker for subsequent separation. Filter membranes of each pore size are fabricated into a specified geometric shape and measured in the high-purity germanium gamma spectrometer for 24 hours. Based on the initial sample measurement results, the nuclides with the highest radioactivity concentration are ranked from lowest to highest. The method involves separating samples sequentially, with each sample further separated according to the pore size of the filter membrane from largest to smallest. The filter membrane is replaced during the filtration process based on the separation results. Finally, filter membranes of the same particle size in the same group are placed on a petri dish and numbered, then dried in an oven to constant weight before measurement. The filtrate is shaken well, and a certain volume is measured and placed in a sample bottle for measurement. This disclosed embodiment provides a method for measuring the particle size distribution of γ-nuclides, enabling the separation and measurement of γ-nuclides in liquid effluents from nuclear power plants. The method is simple, easy to operate, and low in cost. Experiments can reveal the particle size distribution and activity concentration of γ-nuclides in liquid effluents, providing support for the selection of upstream and downstream purification equipment and process optimization in nuclear power plants. Attached Figure Description

[0021] Figure 1 A flowchart illustrating a method for measuring the particle size distribution of γ nuclides provided in this embodiment of the disclosure. Detailed Implementation

[0022] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] Currently, there is limited domestic research on the particle size distribution of radionuclides in liquid effluents from nuclear power plants. Limited international research suggests that radionuclides exist in liquid effluents not as ions, but rather as clusters or particles, and that the particle size of the radionuclides' carriers may be related to their activity concentration. Establishing methods for measuring the particle size distribution in liquid effluents from nuclear power plants and their upstream influent is crucial for a deeper understanding of the physicochemical properties of radionuclides in these effluents.

[0025] Therefore, this disclosure provides a method for measuring the particle size distribution of γ nuclides, which can determine the particle size distribution and activity concentration of different nuclides in liquid effluents.

[0026] At least one embodiment of this disclosure provides a method for measuring the particle size distribution of γ-nuclides, including:

[0027] Initial sample measurement: After adding distilled water to the radionuclide sample adsorbed on the sample container wall and stirring evenly, a certain volume is measured, weighed, and placed into a sample bottle for measurement using a high-purity germanium gamma spectrometer. After the measurement is completed, specifically, after thorough mixing, a certain volume of sample is extracted according to the volume source size of the high-purity germanium gamma spectrometer efficiency scale, and the sample is poured back into the corresponding beaker for subsequent separation, first separating the nuclides adsorbed on the container wall.

[0028] Measurement of blank samples: Randomly select multiple filter membranes of each pore size, specifically 10 filter membranes of each pore size, and fabricate the filter membranes into a specified geometric shape. The specific shape needs to be determined according to the actual operating conditions, such as the commonly used circular or elliptical shape, and place them in a high-purity germanium gamma spectrometer for 24 hours for measurement.

[0029] Separation of radioactive nuclide particle size: Based on the measurement results of the initial sample, the nuclide with the highest radioactivity concentration is sorted from low to high and separated sequentially. Each sample is then separated sequentially according to the filter membrane pore size from large to small, and the filter membrane is replaced during the filtration process according to the separation results.

[0030] Measurement of radionuclide particle size: Filter membranes of the same particle size in the same group are placed on a petri dish and numbered. They are then dried in an oven to constant weight before measurement. Specifically, after drying to constant weight, they are pressed into a sample box for measurement. After filtration, the filtrate is shaken well and a certain volume is measured and placed into a sample bottle for measurement.

[0031] In the above-described method for measuring the particle size distribution of gamma nuclides provided in this embodiment, a certain volume of the radioactive nuclide sample adsorbed on the sample container wall is first stirred with distilled water, weighed, and then placed into a sample bottle for measurement using a high-purity germanium gamma spectrometer. After measurement, the sample is returned to the corresponding beaker for subsequent separation. Filter membranes of each pore size are fabricated into a specified geometric shape and measured in a high-purity germanium gamma spectrometer for 24 hours. Based on the measurement results of the initial sample, the nuclides with the highest radioactivity concentration are ranked from low to high. The method involves separating samples sequentially, with each sample further separated according to the pore size of the filter membrane from largest to smallest. The filter membrane is replaced during the filtration process based on the separation results. Finally, filter membranes of the same particle size in the same group are placed on a petri dish and numbered, then dried in an oven to constant weight before measurement. The filtrate is shaken well, and a certain volume is measured and placed in a sample bottle for measurement. This disclosed embodiment provides a method for measuring the particle size distribution of γ-nuclides, enabling the separation and measurement of γ-nuclides in liquid effluents from nuclear power plants. The method is simple, easy to operate, and low in cost. Experiments can reveal the particle size distribution and activity concentration of γ-nuclides in liquid effluents, providing support for the selection of upstream and downstream purification equipment and process optimization in nuclear power plants.

[0032] Optionally, the radionuclide sample adsorbed on the wall of the sample container can be shaken off, transferred to a beaker, rinsed with distilled water, and then transferred to the beaker and stirred evenly.

[0033] Optionally, a high-frequency ultrasonic oscillation method can be used to vibrate and remove the radionuclides adsorbed on the container wall. The frequency of the high-frequency ultrasonic cleaner is 60kHz and the oscillation time is 6h.

[0034] Optionally, the energy resolution (FWHM) of the high-purity germanium gamma spectrometer is less than 2.0 keV (60Co, 1332.5 keV).

[0035] Optionally, the filter membrane can be fabricated into a specified geometry using a pressing machine with a pressure of 10 tons or more.

[0036] Optionally, the shape and size of the filter membrane can be the same as those of the efficiency calibration standard source.

[0037] Optionally, the filter membrane can be made of polypropylene.

[0038] Optionally, the filtration process is carried out at a constant pressure of 0.07 MPa, specifically through a filtration device, which includes a filtration pump, a filtration flask, a sand core funnel, a clamp, and a filter membrane. The sand core funnel is a G1 glass sand core funnel.

[0039] Optionally, to avoid the influence of changes in the pore size of the filter membrane during the filtration process, the filtration time for every 50 mL of sample is recorded. If the change exceeds 3 seconds, the filter membrane is replaced; otherwise, the filter membrane is replaced every 5 minutes.

[0040] Optionally, the drying temperature is 60°C.

[0041] The present disclosure will now be described through several specific embodiments. To keep the following description of the embodiments of the present disclosure clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present disclosure appears in more than one drawing, that component may be referred to by the same reference in each drawing.

[0042] Figure 1 A flowchart of a method for measuring the particle size distribution of γ-nuclides provided in this disclosure is shown below. Figure 1 As shown, the specific steps for measuring the particle size distribution of γ-nitrites in the liquid effluent and upstream influent of a pressurized water reactor nuclear power plant are as follows:

[0043] (1) Five liquid effluent samples from pressurized water reactor nuclear power plants were collected in this experiment. The sample volume of each sample was slightly more than 1L. The sample container was placed in an ultrasonic cleaner and continuously oscillated at a frequency of 60kHz for 6 hours. After oscillation, the sample was shaken well, and 200mL of each sample was measured and placed in a sample bottle for measurement by a high-purity germanium gamma spectrometer. The measurement time for each sample was 4 hours. After the measurement was completed, the sample was poured back into the sample container.

[0044] (2) Prepare 5 clean empty beakers, number them, and weigh them. Use a graduated cylinder to measure 1L of liquid effluent sample from each beaker and transfer it to the designated numbered beaker. Weigh the sample again. Rinse the graduated cylinder 3 times with 100mL of distilled water, transferring the rinsing solution to the beaker. The volume of the rinsing solution should also be included in the total sample volume. To prevent cross-contamination, after measuring the sample, rinse the graduated cylinder with distilled water and dry it in an oven before measuring subsequent samples.

[0045] (3) The particle sizes selected in this experiment were <0.1μm, 0.1~0.45μm, 0.45~1μm, 1~5μm and >5μm. The filter membranes used had pore sizes of 0.1μm, 0.45μm, 1μm and 5μm, a total of 4 specifications. Ten filter membranes of each specification were randomly selected and pressed into a geometric shape of φ75mm×10mm using a membrane press. They were placed in a sample box and sealed. The samples were measured in a high-purity germanium gamma spectrometer for 24 hours, and the measurement results of the blank samples were recorded.

[0046] (4) Based on the measurement results of the initial sample, sort the five samples from low to high according to the measurement results of the radionuclide with the highest radioactivity concentration, and separate the five samples in sequence. Before separation, number and weigh the filter membranes used in sequence, and record the mass of the blank filter membrane.

[0047] (5) Each sample is separated sequentially according to the filter membrane pore size from largest to smallest. During separation, the filter membrane of the corresponding pore size is fixed on the G1 sand core funnel using a clamp, and the sample is filtered using a vacuum filtration device. To avoid filter membrane clogging affecting the pore size and to ensure consistent filtration efficiency, a constant pressure of 0.07MPa is maintained throughout the filtration process. The filtration time for every 50mL of sample is recorded. The filter membrane is replaced if the filtration time varies by more than 3 seconds; otherwise, the filter membrane is replaced every 5 minutes.

[0048] (6) Wash the beaker containing the sample with 100mL of distilled water more than 3 times, and filter the washing solution as well to avoid possible loss of nuclides. The volume of the washing solution is also included in the total volume of the sample.

[0049] (7) After filtration, filter membranes of the same particle size in the same group are placed on a petri dish and numbered. They are then dried in an oven at 60°C until constant weight. Four groups of filter membranes with particle sizes of 0.1μm~0.45μm, 0.45μm~1μm, 1μm~5μm and >5μm are obtained in sequence. The filter membranes are placed on a petri dish, weighed, and then pressed into a φ75mm×10mm sample box and sealed. They are then placed in a γ spectrometer for measurement to obtain the γ nuclide activity concentration in each particle size range.

[0050] (8) After filtration, shake the filtrate well and measure 200 mL again with a graduated cylinder. Weigh it and put it into a sample bottle. Place it in a γ spectrometer for measurement to obtain the γ nuclide activity concentration in the <0.1 μm particle size range.

[0051] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for measuring the particle size distribution of γ-nuclides, characterized in that, include: Initial sample measurement: The radionuclide sample adsorbed on the sample container wall is shaken off and transferred to a beaker. The sample container is rinsed with distilled water and then transferred to the beaker. The mixture is stirred evenly, a certain volume is measured, weighed, and then placed into a sample bottle. The sample is then placed in a high-purity germanium gamma spectrometer for measurement. After the measurement is completed, the sample is poured back into the corresponding beaker for subsequent separation. Measurement of blank samples: Randomly select multiple filter membranes of each pore size, fabricate the filter membranes into the specified geometric shape, and place them in a high-purity germanium gamma spectrometer for 24 hours for measurement; Separation of radioactive nuclide particle size: Based on the measurement results of the initial sample, the nuclide with the highest radioactivity concentration is sorted from low to high and separated sequentially. Each sample is then separated sequentially according to the filter membrane pore size from large to small, and the filter membrane is replaced during the filtration process according to the separation results. Measurement of radionuclide particle size: Place filter membranes of the same particle size in the same group on a petri dish and number them. Dry them in an oven until constant weight and then measure them. After filtration, shake the filtrate well and measure a certain volume into a sample bottle for measurement.

2. The method for measuring the particle size distribution of γ-nuclides as described in claim 1, characterized in that, The radionuclides adsorbed on the container wall were oscillated and detached by high-frequency ultrasonic oscillation. The frequency of the high-frequency ultrasonic cleaner was 60 kHz, and the oscillation time was 6 hours.

3. The method for measuring the particle size distribution of γ-nuclides as described in claim 1, characterized in that, The energy resolution of the high-purity germanium gamma spectrometer was characterized by FWHM, which is less than 2.0 keV. 60 The value was measured at 1332.5 keV for Co.

4. The method for measuring the particle size distribution of γ-nuclides as described in claim 1, characterized in that, The filter membrane is made into a specified geometric shape using a pressing machine, wherein the pressure of the pressing machine is greater than or equal to 10 tons.

5. The method for measuring the particle size distribution of γ-nuclides as described in claim 4, characterized in that, The shape and size of the filter membrane are consistent with those of the efficiency calibration standard source.

6. The method for measuring the particle size distribution of γ-nuclides as described in claim 5, characterized in that, The filter membrane is made of polypropylene.

7. The method for measuring the particle size distribution of γ-nuclides as described in claim 1, characterized in that, The filtration process is conducted at a constant pressure of 0.07 MPa.

8. The method for measuring the particle size distribution of γ-nuclides as described in claim 1, characterized in that, To avoid the influence of changes in the pore size of the filter membrane during the filtration process, the filtration time for every 50 mL of sample was recorded. The filter membrane was replaced when the filtration time changed by more than 3 seconds, otherwise it was replaced every 5 minutes.

9. The method for measuring the particle size distribution of γ-nuclides as described in claim 1, characterized in that, The drying temperature is 60°C.

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