1. A joint analysis method for the contents of Pu, Am and U in aerosol is characterized by comprising the following steps:

(1) collecting and pretreating a sample: burning the collected aerosol sample, and adding into the aerosol sample with a certain activity²⁴²Pu or²³⁶Pu、²³²U、²⁴³Am is used as a tracer;

(2) leaching: soaking a sample to be detected in hydrofluoric acid, evaporating to dryness, adding nitric acid, heating and leaching, taking filter residue, adding hydrochloric acid, heating and leaching, taking filtrate, and combining the filtrate with the filtrate obtained after heating and leaching by nitric acid;

(3) precipitation and dissolution: adding Fe to the combined filtrates³⁺Adding ammonia water into the carrier solution to adjust the pH value, then precipitating, centrifugally collecting the precipitate, and dissolving the precipitate by using nitric acid;

(4) adjusting the Pu valence: adding a ferrous sulfamate solution into the solution obtained by dissolving in the step (3) for reduction, and then adding a sodium nitrite solution for oxidation;

(5) anion exchange resin column purification and measurement: passing the sample solution obtained in the step (4) through an anion exchange resin column, combining the collected effluent with nitric acid and hydrochloric acid leacheate for analysis of Am and U, collecting HCl-HF solution system eluent, evaporating to dry, plating a wafer electrodeposition source, and measuring by using an alpha spectrometer for Pu;

(6) TRU resin column purification and measurement: passing the combined solution for analysis of Am and U obtained in the step (5) through a TRU resin column in a nitric acid system, eluting the column with nitric acid, a nitric acid-sodium nitrite solution system and nitric acid in sequence, then eluting the column with hydrochloric acid to remove Am, then eluting the U with an ammonium oxalate solution, evaporating the Am eluent and the U eluent respectively to dry, plating a wafer electrodeposition source, and then respectively measuring the Am eluent and the U by an alpha spectrometer;

(7) and (3) calculating the content: and calculating the activity concentrations of Pu, Am and U in the tested sample according to the alpha spectrometer counts of the tracer and the tested nuclide and the known activity of the tracer.

2. The joint analysis method according to claim 1, characterized in that: in the step (1), the²⁴²Pu or²³⁶Pu、²³²U、²⁴³The activity of Am is independently 0.03-1.0 Bq.

3. The joint analysis method according to claim 1, characterized in that: in the step (2), the concentration of the nitric acid is 3-10mol/L, and the adding volume is 25-200 mL; the concentration of the hydrochloric acid is 3-9mol/L, and the adding volume is 25-200 mL.

4. The joint analysis method according to claim 1, characterized in that: in the step (3), the pH value is adjusted to 8-9 by adding ammonia water.

5. The joint analysis method according to claim 1, characterized in that: in the step (4), the concentration of the ferrous sulfamate solution is 0.5-2mol/L, and the reduction time is 5-20 min; the concentration of the sodium nitrite solution is 3-5mol/L, and the oxidation time is 5-20 min.

6. The joint analysis method according to claim 1, characterized in that: in the step (5), the anion exchange resin column is a 205 type anion exchange resin column.

7. The joint analysis method according to claim 1, characterized in that: in the step (5), the concentration of the nitric acid is 7-8 mol/L; the concentration of the hydrochloric acid is 7-10 mol/L; the concentration of HCl in the HCl-HF solution system is 0.2-0.4mol/L, and the concentration of HF is 0.005-0.002 mol/L.

8. The joint analysis method according to claim 1, characterized in that: in the step (6), the concentrations of nitric acid for successively leaching the columns are respectively 1-4mol/L and 0.1-2 mol/L; the concentration of nitric acid in the nitric acid-sodium nitrite solution system is 1-4mol/L, and the concentration of sodium nitrite is 3-5 mol/L; the concentration of the hydrochloric acid is 2-5 mol/L; the concentration of the ammonium oxalate solution is 0.05-0.5 mol/L.

9. The joint analysis method according to claim 1, characterized in that: in the step (5) and the step (6), the current density of the electrodeposition is 500-²The time is 0.5-3 h.

10. The joint analysis method according to claim 1, characterized in that: in the step (7), the step (c),^239+240the calculation formula of the activity concentration of Pu is as follows:

wherein:

A_239+240Pu: in the aerosol sample to be measured^239+240Concentration of Pu Activity in Bq/m³；

A_242Pu: tracer agent²⁴²Pu addition, unit: bq;

N_239+240Pu: on the plated sheet^239+240A count of Pu;

N_242Pu: on the plated sheet²⁴²A count of Pu;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁸The calculation formula of the activity concentration of Pu is as follows:

wherein:

A_238Pu: in the aerosol sample to be measured²³⁸Activity of PuConcentration, unit Bq/m³；

A_242Pu: tracer agent²⁴²Pu addition, unit: bq;

N_238Pu: on the plated sheet²³⁸A count of Pu;

N_242Pu: on the plated sheet²⁴²A count of Pu;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²⁴¹The formula for calculating the activity concentration of Am is as follows:

wherein:

A_241Am: in the aerosol sample to be measured²⁴¹Am Activity concentration, Unit Bq/m³；

A_243Am: tracer agent²⁴³Am addition, unit: bq;

N_241Am: on the plated sheet²⁴¹Am is counted;

N_243Am: on the plated sheet²⁴³Am is counted;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁸The formula for calculating the activity concentration of U is:

wherein:

A_238U: in the aerosol sample to be measured²³⁸U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_238U: on the plated sheet²³⁸Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁴The formula for calculating the activity concentration of U is:

wherein:

A_234U: in the aerosol sample to be measured²³⁴U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_234U: on the plated sheet²³⁴Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁵The formula for calculating the activity concentration of U is:

wherein:

A_235U: in the aerosol sample to be measured²³⁵U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_235U: on the plated sheet²³⁵Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³。

Background

After the occurrence of the nuclear accident of the Japanese Fudao, China puts higher requirements on the construction and the operation of nuclear facilities. Meanwhile, with the higher and higher requirements of national environmental protection, the continuous strengthening of public environmental protection consciousness and the implementation of energy-saving and emission-reducing policies improve the level of related analysis technologies, and have great significance in ensuring that related units can better complete environmental monitoring and evaluation work.

Pu and Am are ubiquitous in the world due to nuclear tests, and the sources of local areas also include nuclear technology utilization, nuclear accidents and the like. U belongs to natural nuclide, and some artificial activities can increase the content of U in an environmental medium. These nuclides are alpha nuclides with a long half-life, among which²³⁸Pu、²³⁹Pu、²⁴⁰Pu、²³⁴U、²⁴¹Am is extremely toxic and can enter human bodies through various ways to cause long-term continuous irradiation, thus harming human health and seriously causing cancer.

In order to better protect the environment and human health, the analysis of Pu, Am and U in the aerosol is a very important object for relevant units and supervision departments, which is not only related to the effective implementation of the estimation of irradiation dose and protective measures in personnel, but also ensures that the workers are effectively protected and can promote the virtuous cycle development of nuclear energy cause. At present, no standard method for analyzing Pu, Am and U mononucleotides in aerosol media exists in China, and no combined analysis method exists. Conventional aerosol media also measure only the total uranium content without performing isotope analysis, which affects the accuracy of internal radiation dose estimation, which is disadvantageous for the development of environmental monitoring and dose estimation work.

At present, some technical bottleneck problems still exist in the aspects of Pu, Am and U isotope radiation monitoring management in aerosol, mainly because the isotope content in the aerosol is extremely low, the analysis difficulty is high, and many units do not have accurate and reliable analysis means. Moreover, the sampling time of the aerosol sample is longer, and the sampling workload of the aerosol is increased if single nuclide analysis is carried out. Therefore, research needs to be carried out on the combined analysis method of the content of Pu, Am and U in the aerosol so as to fill up the technical blank in the aspect, provide technical support for environmental evaluation, dosage estimation and other research, and protect the environment and the health of personnel.

Disclosure of Invention

The invention aims to provide a combined analysis method for the content of Pu, Am and U in aerosol, so that a single aerosol sample multi-nuclide analysis result can be obtained, the stability is good, the accuracy is high, the workload of aerosol sample collection is reduced, and the process and time of nuclide analysis are shortened.

To achieve this object, in a basic embodiment, the present invention provides a method for jointly analyzing the contents of Pu, Am, and U in an aerosol, the method comprising the steps of:

(1) collecting and pretreating a sample: burning the collected aerosol sample, and adding into the aerosol sample with a certain activity²⁴²Pu or²³⁶Pu、²³²U、²⁴³Am is used as a tracer;

(2) leaching: soaking a sample to be detected in hydrofluoric acid, evaporating to dryness, adding nitric acid, heating and leaching, taking filter residue, adding hydrochloric acid, heating and leaching, taking filtrate, and combining the filtrate with the filtrate obtained after heating and leaching by nitric acid;

(3) precipitation and dissolution: adding Fe to the combined filtrates³⁺Adding ammonia water into the carrier solution to adjust the pH value, then precipitating, centrifugally collecting the precipitate, and dissolving the precipitate by using nitric acid;

(4) adjusting the Pu valence: adding a ferrous sulfamate solution into the solution obtained by dissolving in the step (3) for reduction, and then adding a sodium nitrite solution for oxidation;

(5) anion exchange resin column purification and measurement: passing the sample solution obtained in the step (4) through an anion exchange resin column, combining the collected effluent with nitric acid and hydrochloric acid leacheate for analysis of Am and U, collecting HCl-HF solution system eluent, evaporating to dry, plating a wafer electrodeposition source, and measuring by using an alpha spectrometer for Pu;

(6) TRU resin column purification and measurement: passing the combined solution for analysis of Am and U obtained in the step (5) through a TRU resin column in a nitric acid system, eluting the column with nitric acid, a nitric acid-sodium nitrite solution system and nitric acid in sequence, then eluting the column with hydrochloric acid to remove Am, then eluting the U with an ammonium oxalate solution, evaporating the Am eluent and the U eluent respectively to dry, plating a wafer electrodeposition source, and then respectively measuring the Am eluent and the U by an alpha spectrometer;

(7) and (3) calculating the content: and calculating the activity concentrations of Pu, Am and U in the tested sample according to the alpha spectrometer counts of the tracer and the tested nuclide and the known activity of the tracer.

In a preferred embodiment, the present invention provides a method for the joint analysis of the content of Pu, Am and U in aerosol, wherein in step (1), the method is used for the joint analysis of the content of Pu, Am and U in aerosol²⁴²Pu or²³⁶Pu、²³²U、²⁴³The activity of Am is independently 0.03-1.0 Bq.

In a preferred embodiment, the invention provides a combined analysis method for the content of Pu, Am and U in aerosol, wherein in the step (2), the concentration of nitric acid is 3-10mol/L, and the volume of nitric acid is 25-200 mL; the concentration of the hydrochloric acid is 3-9mol/L, and the adding volume is 25-200 mL.

In a preferred embodiment, the invention provides a method for jointly analyzing the content of Pu, Am and U in aerosol, wherein in the step (3), ammonia water is added to adjust the pH value to 8-9.

In a preferred embodiment, the invention provides a combined analysis method for the content of Pu, Am and U in aerosol, wherein in the step (4), the concentration of the ferrous sulfamate solution is 0.5-2mol/L, and the reduction time is 5-20 min; the concentration of the sodium nitrite solution is 3-5mol/L, and the oxidation time is 5-20 min.

In a preferred embodiment, the present invention provides a method for jointly analyzing the content of Pu, Am and U in aerosol, wherein in step (5), the anion exchange resin column is a 205-type anion exchange resin column.

In a preferred embodiment, the invention provides a combined analysis method for the content of Pu, Am and U in aerosol, wherein in the step (5), the concentration of the nitric acid is 7-8 mol/L; the concentration of the hydrochloric acid is 7-10 mol/L; the concentration of HCl in the HCl-HF solution system is 0.2-0.4mol/L, and the concentration of HF is 0.005-0.002 mol/L.

In a preferred embodiment, the invention provides a combined analysis method for the content of Pu, Am and U in aerosol, wherein in the step (6), the concentration of nitric acid for successively eluting columns is 1-4mol/L and 0.1-2mol/L respectively; the concentration of nitric acid in the nitric acid-sodium nitrite solution system is 1-4mol/L, and the concentration of sodium nitrite is 3-5 mol/L; the concentration of the hydrochloric acid is 2-5 mol/L; the concentration of the ammonium oxalate solution is 0.05-0.5 mol/L.

In a preferred embodiment, the present invention provides a method for the combined analysis of the content of Pu, Am and U in aerosol, wherein in step (5) and step (6), the current density of electrodeposition is 500-1200mA/cm²The time is 0.5-3 h.

In a preferred embodiment, the present invention provides a method for the joint analysis of the content of Pu, Am and U in an aerosol, wherein in step (7),

^239+240the calculation formula of the activity concentration of Pu is as follows:

wherein:

A_239+240Pu: in the aerosol sample to be measured^239+240Concentration of Pu Activity in Bq/m³；

A_242Pu: tracer agent²⁴²Pu addition, unit: bq;

N_239+240Pu: on the plated sheet^239+240A count of Pu;

N_242Pu: on the plated sheet²⁴²A count of Pu;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁸The calculation formula of the activity concentration of Pu is as follows:

wherein:

A_238Pu: in the aerosol sample to be measured²³⁸Concentration of Pu Activity in Bq/m³；

A_242Pu: tracer agent²⁴²Pu addition, unit: bq;

N_238Pu: on the plated sheet²³⁸A count of Pu;

N_242Pu: on the plated sheet²⁴²A count of Pu;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²⁴¹The formula for calculating the activity concentration of Am is as follows:

wherein:

A_241Am: in the aerosol sample to be measured²⁴¹Am Activity concentration, Unit Bq/m³；

A_243Am: tracer agent²⁴³Am addition, unit: bq;

N_241Am: on the plated sheet²⁴¹Am is counted;

N_243Am: on the plated sheet²⁴³Am is counted;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁸The formula for calculating the activity concentration of U is:

wherein:

A_238U: in the aerosol sample to be measured²³⁸U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_238U: on the plated sheet²³⁸Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁴The formula for calculating the activity concentration of U is:

wherein:

A_234U: in the aerosol sample to be measured²³⁴U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_234U: on the plated sheet²³⁴Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

²³⁵The formula for calculating the activity concentration of U is:

wherein:

A_235U: in the aerosol sample to be measured²³⁵U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_235U: on the plated sheet²³⁵Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³。

The method has the advantages that by using the method for jointly analyzing the content of Pu, Am and U in the aerosol, the analysis result of multiple nuclides in a single aerosol sample can be obtained, the stability is good, the accuracy is high, the workload of aerosol sample collection is reduced, and the procedure and time of nuclide analysis are shortened.

Drawings

FIG. 1 is a flow chart illustrating a method for jointly analyzing the content of Pu, Am and U in an aerosol according to the present invention.

FIG. 2 shows a schematic view of a liquid crystal display device of example 1^239+240Pu、²³⁸Alpha spectrum of Pu measurement.

FIG. 3 shows a schematic view of a liquid crystal display device of example 1²³⁴U、²³⁸U、²³⁵U measured alpha spectrum.

FIG. 4 shows a schematic view of a liquid crystal display device in example 1²⁴¹Am measured alpha spectrum.

Detailed Description

The following description will further describe embodiments of the present invention with reference to the accompanying drawings.

Example 1:

an exemplary flow of the method for jointly analyzing the contents of Pu, Am and U in the aerosol according to the present invention is shown in fig. 1, and includes the following steps:

(1) collecting aerosol samples in certain places of China (the sampling instrument is a large-flow sampler with the flow rate of 1.0 m)³Min), obtaining a tested sample;

(2) cutting the filter membrane sample after collecting the aerosol into fragments, putting the fragments into a crucible, putting the crucible into a muffle furnace, burning the fragments for 2h at 105 ℃, then heating the fragments to 300 ℃, burning the fragments for 2h, heating the fragments to 450 ℃, burning the fragments for 4-8h, and cooling the fragments to room temperature;

(3) adding the sample with activity of 0.03-1.0Bq²⁴²Pu (or)²³⁶Pu)、²³²U、²⁴³Am is used as a tracer;

(4) adding hydrofluoric acid into the sample to be detected, soaking overnight, heating and evaporating on an electric heating plate, and cooling to room temperature;

(5) adding 7.5M nitric acid into the dry sample obtained in the step (4), heating and leaching for 1 time, filtering after heating and leaching, and respectively collecting filtrate and residues;

(6) adding 6M hydrochloric acid into the residue obtained in the step (5), heating and leaching for 1 time, filtering after heating and leaching, combining the filtrate with the filtrate obtained in the step (5), heating, dropwise adding hydrogen peroxide for fading, and cooling to room temperature;

(7) adding 5-50mg of Fe into the sample solution obtained in the step (6)³⁺Adding ammonia water into a carrier solution ferric trichloride solution to adjust the pH value to be about 9, generating brick red precipitate, centrifuging, collecting the precipitate, dissolving the residue with 7.5mol/L nitric acid, and finally controlling the volume to be 50 mL;

(8) adding 0.5mL of 1mol/L ferrous sulfamate solution into the sample solution obtained in the step (7), reducing for 15min, adding 0.5mL of 4mol/L sodium nitrite, oxidizing for 15min, boiling to completely decompose excessive sodium nitrite, and cooling to room temperature;

(9) passing 7.5mol/L nitric acid through a 205X 7 type ion exchange column (bed height 15cm, diameter 1 cm);

(10) and (3) completely passing the sample solution obtained in the step (8) through an ion exchange column at the flow rate of 2mL/min, eluting the column by using 50mL of 7.5mol/L nitric acid and 50mL of 9mol/L hydrochloric acid in sequence, collecting a sample effluent, 7.5mol/L nitric acid and 9mol/L hydrochloric acid eluates, reserving the eluate for Am and U analysis, finally desorbing Pu in the column by using 0.36mol/L HCl-0.01mol/L HF, and collecting about 70mL of Pu desorption solution.

(11) Evaporating the effluent of the step (10) with 7.5mol/L nitric acid and 9mol/L hydrochloric acid leacheate to dryness, and adding NH₄SCN solution testing of Fe³⁺When the test is positive (blood red appears in the solution), a few drops of 1M ascorbic acid are added to convert Fe³⁺Reduction to Fe²⁺(the solution became colorless);

(12) with 10mL of 2M HNO₃Pre-equilibrating the TRU column; the sample solution was then loaded onto a TRU column and 2X 5mL of 2M HNO₃Washing; with 10mL of 2M HNO₃-4M NaNO₂Washing the column to oxidize any Pu³⁺(ascorbic acid reduction of Pu)⁴⁺Formed) back to Pu⁴⁺(ii) a With 5mL of 1M HNO₃Washing the column;

(13) placing a clean container at the lower end of the column, eluting Am from the TRU column with 20mL of 4M HCl, and retaining the eluent;

(14) a clean vessel was placed at the lower end of the column and 20mL of 0.1M ammonium oxalate (NH) was added₄)₂C₂O₄And E, eluting U, and reserving eluent.

(15) Preparation of sample source: and (3) respectively and independently preparing and measuring the Pu eluent obtained in the step (10), the Am eluent obtained in the step (13) and the U eluent obtained in the step (14) by using a sample source, and specifically comprising the following steps:

adding 5mL concentrated nitric acid and 1mL concentrated sulfuric acid into the eluate, placing on an electric heating plate, heating and steaming until white smoke is exhausted, taking down and cooling to room temperature, adding ammonia water to adjust pH to about 2.2, transferring to an electrodeposition device, washing with a solution with pH of 2.2, and holdingThe beaker with the sample is placed for three times, and the washing solution is transferred to an electrodeposition device, and the total volume is controlled to be 20-25 mL. The electrodeposition device is communicated with a power supply in a cold water bath at the temperature of 900-²Electrodeposition at a current density of (3). Adding 1mL of concentrated ammonia water (18mol/L) into an electrodeposition device, continuing electrodeposition for 1min, cutting off a power supply, removing electrodeposition liquid, washing a plated sheet with distilled water and absolute ethyl alcohol in sequence, drying under an infrared lamp, and measuring on a low-background alpha spectrometer;

(16) calculating the contents of Pu, Am and U in the detected aerosol sample: and calculating the activity concentrations of Pu, Am and U in the tested sample according to the alpha spectrometer counting of the tracer and the tested nuclide and the known activity of the tracer. The method comprises the following specific steps:

1)^239+240activity concentration of Pu: according to²⁴²Pu and^239+240pu count ratio and²⁴²pu (or)²³⁶Pu) activity, calculating the activity of the sample to be tested^239+240Pu activity concentration, the calculation formula is shown in formula (1):

wherein:

A_239+240Pu: in the aerosol sample to be measured^239+240Concentration of Pu Activity in Bq/m³；

A_242Pu: tracer agent²⁴²Pu addition, unit: bq;

N_239+240Pu: on the plated sheet^239+240A count of Pu;

N_242Pu: on the plated sheet²⁴²A count of Pu;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

2)²³⁸Activity concentration of Pu: according to²⁴²Pu and²³⁸pu count ratio and²⁴²pu (or)²³⁶Pu) activity, calculating the activity of the sample to be tested²³⁸Pu activity concentration, the calculation formula is shown in formula (2):

wherein:

A_238Pu: in the aerosol sample to be measured²³⁸Concentration of Pu Activity in Bq/m³；

A_242Pu: tracer agent²⁴²Pu addition, unit: bq;

N_238Pu: on the plated sheet²³⁸A count of Pu;

N_242Pu: on the plated sheet²⁴²A count of Pu;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

3)²⁴¹Am activity concentration: according to²⁴¹Am and²⁴³am count ratio of²⁴³Am activity, calculating the measured sample²⁴¹Am activity concentration, and the calculation formula is shown as formula (3):

wherein:

A_241Am: in the aerosol sample to be measured²⁴¹Am Activity concentration, Unit Bq/m³；

A_243Am: tracer agent²⁴³Am addition, unit: bq;

N_241Am: on the plated sheet²⁴¹Am is counted;

N_243Am: on the plated sheet²⁴³Am is counted;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

4)²³⁸Activity concentration of U: according to²³⁸U and²³²u count ratio sum²³²U activity, calculating in the measured sample²³⁸U activity concentration, and the calculation formula is shown as formula (4):

wherein:

A_238U: in the aerosol sample to be measured²³⁸U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_238U: on the plated sheet²³⁸Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

5)²³⁴Activity concentration of U: according to²³⁴U and²³²u count ratio sum²³²U activity, calculating in the measured sample²³⁴U activity concentration, and the calculation formula is shown as formula (5):

wherein:

A_234U: in the aerosol sample to be measured²³⁴U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_234U: on the plated sheet²³⁴Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³，

6)²³⁵Activity concentration of U: according to²³⁵U and²³²u count ratio sum²³²U activity, calculating in the measured sample²³⁵U activity concentration, and the calculation formula is shown as formula (6):

wherein:

A_235U: in the aerosol sample to be measured²³⁵U Activity concentration in Bq/m³；

A_232U: tracer agent²³²U addition, unit: bq;

N_235U: on the plated sheet²³⁵Counting of U;

N_232U: on the plated sheet²³²Counting of U;

e: detecting efficiency;

y: recovery rate;

v: aerosol volume in m³。

The method needs to be noted that the whole-process amplification recovery rate of Pu, Am and U is improved to reduce the detection limit of the method, and the stability of the method is also needed. The specific examination method comprises the following steps: and (3) taking a sample which is actually collected with the aerosol as a tested sample, carrying out nuclide analysis according to the steps (1) to (16), and calculating the size of the whole radiochemical recovery rate and the standard deviation of the recovery rate.

The assay of this example analyzed 6 aerosol samples and the results are shown in tables 1-2 below, and the alpha spectra are shown in FIGS. 2-4.

TABLE 1 Experimental data for the overall radiochemical recovery of Pu, Am, U

TABLE 2 Combined analysis of experimental results for Pu, Am, U in actual aerosol samples

Table 1 the results show that: the joint analysis of Pu, Am and U in the aerosol can be realized by adopting 205 × 7 type anion exchange resin and TRU resin; the recovery rates of Pu, U and Am are respectively (85.4 +/-7.6)%, (93.1 +/-3.5)% and (88.5 +/-6.3)%; the method has high recovery rate, and the recovery rates of Pu, U and Am are all higher than 80%; the method has good stability, and the standard deviation of the recovery rate is better than 10%.

According to the analysis of the experimental data in the table 2, the method can be used for measuring the isotopes of Pu, Am and U in the aerosol sample, and the content is 10^-8～10^-9Bq/m³And (4) horizontal. In aerosol samples^239+240The content range of Pu is 0.02-0.96 mu Bq/m³，²³⁸The content range of Pu is 0.01-0.30 mu Bq/m³，²³⁸The U content is 0.08-0.31 mu Bq/m³，²³⁴The U content is in the range of 0.11-0.46 mu Bq/m³，²³⁵The content range of U is<0.001～0.021μBq/m³，²⁴¹The content range of Am is 0.07-0.25 mu Bq/m³。

The method needs to pay attention to the separation and purification effects of Pu, U and Am. The specific examination method comprises the following steps: and (3) taking a sample which is actually collected with the aerosol as a detected sample, carrying out nuclide analysis according to the steps (1) to (16), and identifying the removal effect of the interfering nuclide through an alpha spectrogram measured by each nuclide.

As can be seen from fig. 2-4: the resolution of alpha energy peaks of Pu, Am and U isotopes is good, and other interfering nuclides are almost completely leached, so that the resin can well realize the separation of the nuclide to be detected and other nuclides.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations. The foregoing examples or embodiments are merely illustrative of the present invention, which may be embodied in other specific forms or in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims should be construed to be included therein.