A method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor

Abstract

This invention discloses a method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor, belonging to the field of radioactive material measurement technology. 210 Po solution was used to prepare test samples with different activity ranges and different collection carriers, and the activity was measured using an energy dispersive spectrometer. A correlation between the measured activity and the theoretical activity was then established to calibrate the measured activity of actual samples. This invention employs the above-mentioned method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor, by flexibly establishing a correlation between the measured activity and the theoretical activity within a certain activity range. 210 The linear correlation between the theoretical activity and the measured activity of the Po standard solution enables immediate measurement without disturbing the original sample, greatly ensuring the accuracy of the measurement. This is of great significance for timely and effective protection in lead-bismuth reactors. At the same time, this method can also be applied to other environments to quickly and accurately obtain the true activity of polonium-containing samples.

Description

Technical Field

[0001] This invention relates to the field of radioactive material measurement technology, and in particular to a method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor. Background Technology

[0002] With the rapid development of modern nuclear energy technology, lead-cooled fast reactors have become one of the most promising reactor technologies, possessing significant advantages in safety, nuclear waste transmutation, nuclear fuel breeding, and economics. However, in lead-cooled fast reactor systems using lead-bismuth alloys as coolants or target materials, these alloys are highly susceptible to neutron activation, producing pure lead-bismuth alloys. Radionuclides 210 Po, which primarily spreads in the environment as an aerosol, is a common pollutant. It can be detected during maintenance and in the event of a coolant leak. 210 Polonium (P) and its vapor in the protective gas will diffuse out of the main system and be released into the atmosphere, posing a significant threat to human health and the natural environment. Therefore, it is essential to accurately and efficiently measure the released radioactive polonium activity in order to implement more targeted protective measures.

[0003] Currently, there are many methods for measuring the activity of radioactive polonium, including electrodeposition, microprecipitation, autoprecipitation, and chromatography-extraction. The national standard for the analysis of polonium-210 in water (HJ813-2016) uses an electroplating method for sample preparation, which involves adding... 209 Po tracer, utilizing ferric hydroxide adsorption carrier 209 Po and 210 Po forms a precipitate, which is then dissolved in hydrochloric acid, followed by the addition of ascorbic acid and hydroxylamine hydrochloride to reduce Fe. 3+ During the reduction process, heating and stirring are required to promote the process. 209 Po and 210 Po self-deposits on the surface of a silver sheet. Although electrodeposition has become an industry standard, this method is suitable for the processing of liquid samples. The overall operation is cumbersome, and the sample preparation time often takes several hours or longer. For solid samples, they need to be further dissolved into liquid before sample preparation and testing. At the same time, the influence of impurity ions in the process cannot be ignored.

[0004] Microprecipitation is a commonly used method for preparing low-content polonium sources. Existing technology publication CN110988962A describes a rapid analytical method for polonium-210 in aerosols. This method involves cutting the collected aerosol sample into fragments, dissolving them in hydrochloric acid, centrifuging to collect the filtrate, repeating this process several times, collecting the filtrate, and then adding... 209Po tracer, Te(VI) or Te(IV), reducing agent, and organic solvent are used in a reduction reaction to obtain TeO2 or elemental Te, which can precipitate the radioactive polonium-210 carrier. This carrier is then dispersed on the filter membrane surface after filtration to obtain the sample to be tested. Compared to electroplating, the microprecipitation method requires no complex equipment and saves time. However, this method is subject to human interference with the original sample, and the addition of impurity ions cannot guarantee that the measurement accuracy will not be affected.

[0005] The self-deposition method involves the electrochemical reaction of polonium in a hydrochloric acid system under high temperature conditions, where polonium is deposited onto the surface of metal sheets such as silver, copper, and nickel, thus obtaining polonium-containing samples. Although this method has been widely used, the temperature needs to reach 80-95 degrees Celsius. Therefore, polonium may be lost, and the process is lengthy, typically 3-6 hours. Chromatographic extraction suffers from low efficiency and high solvent consumption in the separation of low-concentration polonium, making it unsuitable for processing polonium aerosol samples.

[0006] Research on the analysis and measurement of polonium aerosol activity generated from irradiated lead-bismuth alloys is extremely scarce. Furthermore, the biggest common problem with existing analytical methods is that they all require a series of processing steps on the original sample to obtain the sample to be tested, preventing immediate measurement. This significantly perturbs the polonium content and greatly reduces the accuracy of the measurement. Therefore, existing analytical methods are not suitable for accurately measuring the activity of radioactive polonium aerosols released from lead-bismuth reactors. Therefore, it is necessary to develop more efficient and simpler methods and approaches for measuring polonium aerosol activity. Summary of the Invention

[0007] The purpose of this invention is to provide a method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor, by flexibly establishing a certain activity range. 210 The linear correlation between the theoretical activity and the measured activity of the Po standard solution enables immediate measurement without disturbing the original sample, greatly ensuring the accuracy of the measurement. This is of great significance for timely and effective protection in lead-bismuth reactors. At the same time, this method can also be applied to other environments to quickly and accurately obtain the true activity of polonium-containing samples.

[0008] To achieve the above objectives, the present invention provides a method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor, comprising the following steps:

[0009] S1, will 210 Po solution, nitric acid, and UP water were used to prepare a primary radioactive diluent;

[0010] S2. After dissolving the lead-bismuth alloy with nitric acid, dilute the solution with UP water to prepare a lead-bismuth alloy solution.

[0011] S3. The primary radioactive diluent is mixed with UP water and lead-bismuth alloy solution respectively to obtain non-interfering secondary radioactive diluent and radionuclide-interfering secondary radioactive diluent.

[0012] S4. Take the non-interfering secondary radioactive diluent and the radionuclide interference secondary radioactive diluent, spread them evenly on the surface of the sample collection carrier, and then allow them to evaporate naturally at low temperature to obtain a dried sample. Then, pass the dried sample through... Its activity was measured using an energy dispersive spectrometer;

[0013] S5. Add the following to each sample. 210 The theoretical activity of the Po standard solution was linearly fitted to the corresponding measured activity, and the resulting standard curve was used to calibrate the measured activity of polonium-containing samples.

[0014] Preferably, in S1, the concentration range of the primary radioactive diluent is 0.001-100. .

[0015] Preferably, in S2, the amount of lead-bismuth alloy dissolved is fixed at 0.1%-5% of the average volatilization amount of the irradiated lead-bismuth alloy at high temperature.

[0016] Preferably, in S1 and S2, the concentration of nitric acid is 0.1-10. .

[0017] Preferably, in S3, the activity range of both the non-interfering secondary radioactive diluent and the radionuclide-interfering secondary radioactive diluent is 0.0001-10 Bq.

[0018] Preferably, in S4, the carrier is one or more of the following: aluminum sheet, stainless steel sheet, iron sheet, silver sheet, nickel sheet, graphite felt, carbon felt, carbon fiber, silicon carbide fiber, glass fiber, wood fiber, and polypropylene fiber membrane.

[0019] Preferably, the carrier size is 13-51mm.

[0020] Preferably, in step S4, the conditions for natural evaporation are: temperature below 40°C. And dry, The energy dispersive spectrometer test time is 6-48 hours.

[0021] Preferably, in S4, the amount of non-interfering secondary radioactive diluent and the radionuclide interfering secondary radioactive diluent used is 0.01-1 mL.

[0022] Therefore, the method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor described above has the following beneficial effects:

[0023] (1) Compared with existing polonium analysis and measurement methods, the activity measurement method of the present invention is simple to operate, has minimal impact on the polonium content in the original sample, and can be directly batch tested without processing;

[0024] (2) The measurement method in this invention compares the measured activity with the corresponding added [product / product]. 210 The theoretical activity of Po standard solution was compared, and a very consistent linear correlation was found between the two; specifically, in solutions containing only... 210 In the case of Po, the linear fitting coefficient between theoretical and measured activities is 0.99951. In the presence of lead and bismuth, the linear fitting coefficient is 0.9994. This indicates that the main influencing nuclides that co-volatilize have a significant impact on the measured activity. 210 The measurement of Po activity has little impact; that is, within a certain activity range, the true activity of the actual polonium-containing sample can be determined by establishing... 210 The calibration was obtained by establishing a linear correlation between the theoretical activity and the measured activity of the Po standard solution; furthermore, this was applied under different sample collection carriers. 210 The linear correlation coefficient between the theoretical and measured activities of Po remains above 0.99, indicating that the activity of polonium aerosols on the surfaces of different carrier materials can be calibrated very well by establishing a standard curve, thus obtaining the true activity. Furthermore, when collecting polonium aerosols using a carrier, a special high-temperature vacuum grease needs to be applied. In this case, 210 The theoretical activity of Po and The correlation between the activity measured by the spectrometer and the activity measured by the liquid scintillation instrument remained good, indicating that the activity of polonium aerosol on the carrier surface coated with special high-temperature vacuum grease can be calibrated very well by establishing a standard curve, thereby obtaining the true activity.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is the present invention. 210 Correlation diagram of theoretical activity and measured activity of Po;

[0027] Figure 2 The present invention relates to lead and bismuth pairs. 210 Correlation diagram of theoretical activity and measured activity of Po;

[0028] Figure 3 The aluminum sheet of this invention serves as a sample collection carrier. 210 The correlation between the theoretical activity and measured activity of Po, among which... Figure 3 (a) When the activity is 0-4 Bq 210 A linear relationship exists between the theoretical activity and the tested activity of Po. Figure 3(b) When the activity is 0-0.1 Bq 210 A linear relationship between Po theoretical activity and tested activity;

[0029] Figure 4 The present invention uses stainless steel sheets as sample collection carriers. 210 Correlation diagram of theoretical activity and measured activity of Po;

[0030] Figure 5 This invention contains high-temperature vacuum grease. 210 The correlation diagram between the theoretical activity and measured activity of Po is shown, in which... Figure 5 In the figure (a), the theoretical activity is... Correlation diagram of activity measured by spectrometer Figure 5 (b) in the figure shows the correlation between theoretical activity and liquid scintillation measured activity. Figure 5 (c) in the middle is Correlation between spectrometer-measured activity and liquid scintillation-measured activity. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0033] Example 1

[0034] 210 A study on the correlation between the theoretical activity and measured activity of Po:

[0035] (1) 210 Po solution, nitric acid, and UP water are mixed to form a primary solution. 210 Po dilution solution: Take four clean 5mL test tubes and add 0.2mL of 20.5459 mg / L solution to each tube. 10.2730 2.0546 0.5136 Level 1 210 The Po diluent was then diluted with 0.2 mL of UP water to prepare four non-interfering secondary solutions. 210 Po diluent;

[0036] (2) Absorb 10 Level 2 interference-free 210 The Po diluent was evenly spread on the smooth surface of a 25mm diameter aluminum sheet, and the solution was applied 10 times, ensuring symmetrical application and covering the entire surface of the aluminum sheet. Finally, the solution was applied at an ambient temperature below 40°C. The aluminum sheets are naturally dried under certain conditions. The dried aluminum sheets are then passed through a four-channel... The corresponding effective counts were obtained from the energy dispersive spectroscopy (EDS) test, and the formula for calculating the measured activity is as follows:

[0037] ;

[0038] in: For a valid count; For measuring time (s); for Spectrometer detection efficiency; The filter membrane filtration efficiency is set to 1. This is the self-absorption factor of the filter membrane, with a value of 1.

[0039] Experimental results are as follows Figure 1 As shown, by Figure 1 It can be seen that, without the influence of interfering nuclides, the correlation coefficient between theoretical activity and measured activity can reach 0.99951, and the consistency between the two activities remains good.

[0040] Example 2:

[0041] Lead and bismuth 210 The impact of the correlation between the theoretical activity and measured activity of Po on research:

[0042] (1) Weigh 0.025g of lead-bismuth alloy without an oxide layer on the surface, add 1.5mL of 7M nitric acid to dissolve it, and then add UP water to make up to 10mL to prepare a lead-bismuth alloy solution.

[0043] (2) 210 Po solution, nitric acid, and UP water are mixed to form a primary solution. 210 Po dilution solution: Take four clean 5mL test tubes and add 0.2mL of 20.5459 mg / L solution to each tube. 10.2730 2.0546 0.5136 Level 1 210 Po dilution solution was then added, followed by the addition of 0.2 mL of lead-bismuth alloy dissolving solution to prepare four radionuclide interference secondary solutions. 210 Po diluent.

[0044] (3) Absorb 10 Nuclide interference level 2 210 The Po diluent was evenly spread on the smooth surface of a 25mm diameter aluminum sheet, and the solution was applied 10 times, ensuring symmetrical application and covering the entire surface of the aluminum sheet. Finally, the solution was applied at an ambient temperature below 40°C. The aluminum sheets are naturally dried under certain conditions. The dried aluminum sheets are then passed through a four-channel... The corresponding effective counts were obtained from the energy dispersive spectroscopy (EDS) test, and the formula for calculating the measured activity is as follows:

[0045] ;

[0046] in: For a valid count; For measuring time (s); for Spectrometer detection efficiency; The filter membrane filtration efficiency is set to 1. This is the self-absorption factor of the filter membrane, with a value of 1.

[0047] Experimental results are as follows Figure 2 As shown, by Figure 2 It can be seen that when lead and bismuth are present in the solution, the correlation coefficient between the theoretical activity and the measured activity can still reach 0.9994, and the consistency between the two activities remains good. Therefore, lead and bismuth have little impact on the accuracy of the measurement. The measured activity of polonium-containing samples can be calibrated by establishing a standard curve.

[0048] Example 3:

[0049] Aluminum sheet as a sample collection carrier 210 The impact of the correlation between the theoretical activity and measured activity of Po on research:

[0050] (1) Utilization 210 Po standard solution was prepared by adding 7M nitric acid and UP water to a concentration of 50. Level 1 210 Po diluent, then add UP water to make the first stage 210 The Po diluent was diluted to 0.1 g / L. 0.4 0.7 1 and 1 4 7 20 30 40 Secondary activity ranges of two different activity ranges 210 Po diluent;

[0051] (2) Absorb 10 Secondary activity ranges of two different 210 The Po diluent was evenly spread on the smooth surface of a 25mm diameter aluminum sheet, and the solution was applied 10 times, ensuring symmetrical application and covering the entire surface of the aluminum sheet. Finally, the solution was applied at an ambient temperature below 40°C. The aluminum sheets are naturally dried under certain conditions. The dried aluminum sheets are then passed through a four-channel... The corresponding effective counts were obtained from the energy dispersive spectroscopy (EDS) test, and the formula for calculating the measured activity is as follows:

[0052] ;

[0053] in: For a valid count; For measuring time (s); for Spectrometer detection efficiency; The filter membrane filtration efficiency is set to 1. This is the self-absorption factor of the filter membrane, with a value of 1.

[0054] Experimental results are as follows Figure 3 As shown, where Figure 3 (a) When the activity is 0-4 Bq 210 A linear relationship exists between the theoretical activity and the tested activity of Po. Figure 3 (b) When the activity is 0-0.1 Bq 210 Theoretical activity of Po is linearly related to its tested activity. Figure 3 It can be seen that when aluminum sheets are used as the sample collection carrier, the linear correlation coefficients between theoretical activity and measured activity can still reach 0.99645 and 0.99021 within different activity ranges. The decrease in the linear correlation coefficient value is mainly due to fluctuations in the measurement environment, but the usability and calibrability of the relative curves remain high.

[0055] Example 4: Stainless steel sheet as a sample collection carrier 210 The impact of the correlation between the theoretical activity and measured activity of Po on research:

[0056] (1) Utilization 210 Po standard solution was prepared by adding 7M nitric acid and UP water to a concentration of 50. Level 1 210 Po diluent, then add UP water to make the first stage 210 The Po diluent was diluted to 0.1 g / L. 0.4 0.7 1 and 1 4 7 20 30 40 Secondary activity ranges of two different activity ranges 210 Po diluent;

[0057] (2) Absorb 10 Level 2 210The Po diluent was evenly spread on the smooth surface of a 25mm diameter aluminum sheet, and the solution was applied 10 times, ensuring symmetrical application and covering the entire surface of the aluminum sheet. Finally, the solution was applied at an ambient temperature below 40°C. The aluminum sheets are naturally dried under certain conditions. The dried aluminum sheets are then passed through a four-channel... The corresponding effective counts were obtained from the energy dispersive spectroscopy (EDS) test, and the formula for calculating the measured activity is as follows:

[0058] ;

[0059] in: For a valid count; For measuring time (s); for Spectrometer detection efficiency; The filter membrane filtration efficiency is set to 1. This is the self-absorption factor of the filter membrane, with a value of 1.

[0060] Experimental results are as follows Figure 4 As shown, by Figure 4 It can be seen that when stainless steel sheets are used as the sample collection carrier, the linear correlation coefficient between theoretical activity and measured activity can still reach 0.99757 within different activity ranges. The linear correlation coefficient remains good, and the established standard curve has good calibrability for measured activity.

[0061] Example 5:

[0062] High-temperature vacuum grease 210 The impact of the correlation between the theoretical activity and measured activity of Po on research:

[0063] (1) When collecting volatilized polonium aerosols using metal sheets of different collection materials, a specific high-temperature grease needs to be applied for collection. Based on the amount of high-temperature vacuum grease applied when collecting polonium aerosols, the same amount of high-temperature vacuum grease is also applied to the surface of the aluminum sheet, followed by dripping a first-stage grease. 210 Po diluent was evenly spread on the smooth surface of an aluminum sheet with a diameter of 25mm. The solution was absorbed 10 times, and the spread was symmetrical and covered the entire surface of the aluminum sheet.

[0064] (2) When the ambient temperature is below 40°C The aluminum sheets are naturally dried under certain conditions, and the dried aluminum sheets are then passed through a four-channel system. The corresponding effective counts were obtained from the energy dispersive spectroscopy (EDS) test, and the formula for calculating the measured activity is as follows:

[0065] ;

[0066] in: For a valid count; For measuring time (s); for Spectrometer detection efficiency; The filter membrane filtration efficiency is set to 1. This is the self-absorption factor of the filter membrane, with a value of 1.

[0067] After the energy dispersive spectroscopy (EDS) test is completed, the dried aluminum sheet is continued to be immersed in 3 mL of 1 The solution is dissolved in hydrochloric acid, and the dissolved liquid is further tested by a liquid scintillation spectrometer from a professional metrology institution to obtain liquid scintillation spectrometer data.

[0068] Experimental results are as follows Figure 5 As shown, where Figure 5 In the figure (a), the theoretical activity is... Correlation diagram of activity measured by spectrometer Figure 5 (b) in the figure shows the correlation between theoretical activity and liquid scintillation measured activity. Figure 5 (c) in the middle is The correlation graph between spectrometer-measured activity and liquid scintillation-measured activity is shown in the figure. Figure 5 It can be seen that, 210 Po's theoretical activity, The activity measured by spectrometer, the activity measured by liquid scintillation, and the activity all showed a very good linear relationship, indicating that high-temperature oils have a significant impact on the activity of liquid scintillation. 210 The measurement effect of Po is very small, and further evidence is provided by... The spectrometer is highly reliable and accurate in measuring the activity of collected polonium aerosols.

[0069] Therefore, this invention employs the aforementioned method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor, by flexibly establishing within a certain activity range. 210 The linear correlation between the theoretical activity and the measured activity of the Po standard solution enables immediate measurement without disturbing the original sample, greatly ensuring the accuracy of the measurement. This is of great significance for timely and effective protection in lead-bismuth reactors. At the same time, this method can also be applied to other environments to quickly and accurately obtain the true activity of polonium-containing samples.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor, characterized in that, Includes the following steps: S1, will 210 Po solution, nitric acid, and UP water were used to prepare a primary radioactive diluent; S2. After dissolving the lead-bismuth alloy with nitric acid, dilute the solution with UP water to prepare a lead-bismuth alloy solution. S3. The primary radioactive diluent is mixed with UP water and lead-bismuth alloy solution respectively to obtain non-interfering secondary radioactive diluent and radionuclide-interfering secondary radioactive diluent. S4. Take the non-interfering secondary radioactive diluent and the radionuclide interference secondary radioactive diluent, spread them evenly on the surface of the sample collection carrier, and then allow them to evaporate naturally at low temperature to obtain a dried sample. Then, pass the dried sample through... Its activity was measured using an energy dispersive spectrometer; S5. Add the following to each sample. 210 The theoretical activity of Po standard solution was linearly fitted with the corresponding measured activity, and the obtained standard curve was used to calibrate the measured activity of polonium-containing samples. In S4, the formula for calculating the activity of the dried sample is as follows: ； in: For a valid count; For measuring time (s); for Spectrometer detection efficiency; For membrane filtration efficiency; It is the self-absorption factor of the filter membrane.

2. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S1, the concentration range of the primary radioactive diluent is 0.001-100. .

3. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S2, the amount of lead-bismuth alloy dissolved is fixed at 0.1%-5% of the average volatilization amount of the irradiated lead-bismuth alloy at high temperature.

4. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S1 and S2, the nitric acid concentration is 0.1-10. .

5. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S3, the activity range of both the non-interfering secondary radioactive diluent and the radionuclide-interfering secondary radioactive diluent is 0.0001-10 Bq.

6. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S4, the carrier is one or more of the following: aluminum sheet, stainless steel sheet, iron sheet, silver sheet, nickel sheet, graphite felt, carbon felt, carbon fiber, silicon carbide fiber, glass fiber, wood fiber, and polypropylene fiber membrane.

7. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, The carrier size is 13-51mm.

8. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S4, the conditions for natural evaporation are: temperature below 40°C. And dry, The energy dispersive spectrometer test time is 6-48 hours.

9. The method for measuring the activity of radioactive polonium aerosol in a lead-bismuth reactor according to claim 1, characterized in that, In S4, the amount of non-interfering secondary radioactive diluent and radionuclide interfering secondary radioactive diluent used is 0.01-1 mL.

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