Joint analysis method for uranium and plutonium isotopes in water sample

Abstract

The invention relates to a joint analysis method for uranium and plutonium isotopes in a water sample, which comprises the following steps: enriching uranium and plutonium isotopes in a water sample to be detected to obtain a sample dissolving solution; uranium and plutonium in the sample dissolving solution are separated through an anion exchange resin column, and a first uranium component and a first plutonium component are obtained respectively; performing secondary purification on the first uranium component through an anion exchange resin column to obtain a second uranium component, and measuring the content of uranium isotope in the second uranium component; performing secondary purification on the first plutonium component through a TEVA resin column to obtain a second plutonium component, and measuring the content of plutonium isotope in the second plutonium component; the method can be used for measuring and analyzing the isotope content of uranium and plutonium in a sample at the same time so as to achieve the purposes of environment monitoring, workplace radiation hazard characteristic evaluation, dose evaluation, nuclear evidence obtaining and the like. The method provided by the invention has a very good separation effect on uranium and plutonium isotopes, has a very good decontamination effect on radioactive interference nuclides such as thorium isotopes in the sample, and is high in chemical recovery rate and high in analysis efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of radiochemical analysis, and in particular relates to a method for joint analysis of uranium and plutonium isotopes in water samples. Background Art

[0002] In recent decades, the large-scale construction of nuclear power plants has led to the global proliferation of artificial and natural radionuclides in the environment at ultra-trace levels. The release of dangerous radionuclides into the environment caused by nuclear accidents (e.g., Chernobyl and Fukushima) has further exacerbated health and environmental concerns about the use of nuclear energy and the risks associated with nuclear proliferation. In order to respond to emergency situations and routine monitoring, it is necessary to develop simple and rapid radionuclide analysis methods, especially for difficult-to-measure radionuclides that cannot be directly measured by gamma spectrometers. Isotopes of uranium and plutonium ( 234 U. 235 U. 238 U. 239 Pu, 240 Pu, etc.) are important radionuclides that are difficult to measure. Because of their high toxicity and the large amount of activation / fission products produced during the operation of nuclear power reactors, it is often necessary to quickly and accurately determine the content of uranium and plutonium isotopes in different samples, which is essential for environmental monitoring, workplace radiation hazard characteristic assessment, dose assessment, and nuclear forensics.

[0003] Since uranium and plutonium isotopes have similar mass numbers or radiation energies, they need to be chemically separated and purified before measurement to avoid possible analytical interference. Although a variety of methods have been developed for measuring uranium and plutonium radioactive isotopes in environmental and biological samples, they all measure isotopes of single uranium and plutonium elements and are very time-consuming to operate. Summary of the invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for the joint analysis of uranium and plutonium isotopes in water samples, wherein the sample is pretreated and then passed through an anion exchange resin, the plutonium isotopes are retained on the resin column, and the uranium isotopes enter the effluent; the uranium isotopes in the effluent are further purified by the anion exchange resin; the plutonium isotopes are further purified by the TEVA resin column after being purified by the anion exchange resin column; the method has a strong ability to separate uranium and plutonium isotopes, a strong ability to decontaminate radioactive interfering nuclides in the sample, a high chemical recovery rate, and a high analysis efficiency.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: a method for joint analysis of uranium and plutonium isotopes in water samples, the method comprising the following steps:

[0006] S1. Enrich the uranium and plutonium isotopes in the water sample to be tested to obtain a sample solution;

[0007] S2, separating uranium and plutonium in the sample solution by an anion exchange resin column to obtain a first uranium component and a first plutonium component, respectively;

[0008] S3, performing secondary purification on the first uranium component through an anion exchange resin column to obtain a second uranium component and measuring the content of uranium isotopes therein;

[0009] S4. Purify the first plutonium component for a second time through a TEVA resin column to obtain a second plutonium component and measure the plutonium isotope content therein.

[0010] Further, step S1 includes the following specific steps:

[0011] Add a known amount of 242 Pu, 232 U or 233 U standard solution as tracer;

[0012] Adjust the pH of the water sample to be tested to less than 1, add titanium trichloride solution, adjust the pH of the water sample system to 8-10 with ammonia water, shake thoroughly to generate a white first precipitate, centrifuge and discard the supernatant, wash the first precipitate with high-purity water and discard the supernatant;

[0013] The first precipitate is then dissolved with nitric acid, and a sodium nitrite solution is added thereto, and after standing for a certain period of time, a sample solution is obtained.

[0014] Furthermore, in step S1, hydrochloric acid or nitric acid is used to adjust the pH of the water sample to less than 1.

[0015] Furthermore, in step S1, the mass percentage of titanium trichloride in the titanium trichloride solution is 15%, and the volume ratio of the titanium trichloride solution to the water sample to be tested is 1:100 to 1:1000.

[0016] Further, in step S1, the first precipitate is dissolved with 8 mol / L nitric acid, 0.1 mL to 1 mL of 3 mol / L sodium nitrite solution is added, and the mixture is allowed to stand for 5 min to 20 min to obtain the sample solution.

[0017] Further, step S2 includes the following specific steps:

[0018] Passing the sample solution through an anion exchange resin column, eluting the anion exchange resin column with nitric acid and hydrochloric acid in sequence, and then eluting plutonium with a first mixed acid formed by mixing hydrochloric acid and hydrofluoric acid;

[0019] The effluent of the sample solution passing through the anion exchange resin column is combined with the nitric acid eluent to obtain the first uranium component; the first mixed acid eluent is the first plutonium component.

[0020] Furthermore, in step S2, the anion exchange resin column is eluted with 5 to 20 column volumes of 8 mol / L nitric acid and 5 to 20 column volumes of 9 mol / L hydrochloric acid in sequence.

[0021] Furthermore, in step S2, plutonium is eluted using 5 to 20 column volumes of a first mixed acid, wherein the concentration of hydrochloric acid in the first mixed acid is 0.1 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

[0022] Further, step S3 includes the following specific steps:

[0023] adding titanium trichloride solution to the first uranium component, adjusting the pH value of the first uranium component system to 8-10 with ammonia water, centrifuging and discarding the supernatant, washing the obtained second precipitate with high-purity water and discarding the supernatant, then dissolving the second precipitate with HCl, passing the dissolved solution through an anion exchange resin column, eluting the anion exchange resin column with HCl, and then eluting uranium with a second mixed acid mixed with nitric acid and hydrofluoric acid, and the obtained second mixed acid eluate is the second uranium component;

[0024] The uranium isotope content is measured using an alpha spectrometer or an inductively coupled plasma mass spectrometer.

[0025] Further, in step S3, when the content of uranium isotopes in the second uranium component is measured by using an α spectrometer, the second uranium component is prepared as an α source by a microprecipitation method, and the α spectrum of the uranium isotopes therein is measured by using an α spectrometer, and the content of the corresponding uranium isotope is obtained by α counting of characteristic energy peaks in the α spectrum of the uranium isotopes;

[0026] When the content of uranium isotopes in the second uranium component is measured by using an inductively coupled plasma mass spectrometer, the content of the corresponding uranium isotopes is obtained by measuring the number of ions of different uranium isotopes.

[0027] Further, in step S3, the second precipitate is dissolved with 6 mol / L HCl;

[0028] The anion exchange resin column is eluted with 5 to 20 column volumes of 6 mol / L HCl, and then the uranium is eluted with 5 to 20 column volumes of a second mixed acid;

[0029] The concentration of nitric acid in the second mixed acid is 0.2 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

[0030] Further, step S4 includes the following specific steps:

[0031] Add titanium trichloride solution to the first plutonium component, adjust the pH value of the first plutonium component system to 8-10 with ammonia water, shake thoroughly, centrifuge and discard the supernatant, wash the obtained third precipitate with high-purity water and discard the supernatant, then dissolve the third precipitate with nitric acid, add sodium nitrite solution to the dissolving solution, pass through a TEVA resin column, elute the TEVA resin column with nitric acid and hydrochloric acid in turn, and then elute plutonium with a third mixed acid formed by a mixture of hydrochloric acid and hydrofluoric acid, and the obtained third mixed acid eluate is the second plutonium component;

[0032] The plutonium isotope content is measured using an alpha spectrometer or an inductively coupled plasma mass spectrometer.

[0033] Further, in step S4, when the content of plutonium isotopes in the second plutonium component is measured by using an alpha spectrometer, the second plutonium component is prepared as an alpha source by a microprecipitation method, and the alpha spectrum of the plutonium isotopes therein is measured by using an alpha spectrometer, and the content of the corresponding plutonium isotope is obtained by alpha counting of characteristic energy peaks in the alpha spectrum of the plutonium isotopes;

[0034] When the content of plutonium isotopes in the second plutonium component is measured by using an inductively coupled plasma mass spectrometer, the content of the corresponding plutonium isotopes is obtained by measuring the number of ions of different plutonium isotopes.

[0035] Furthermore, in step S4, the third precipitate is dissolved with 8 mol / L nitric acid, 0.1 mL to 1 mL of 3 mol / L sodium nitrite solution is added, and after standing for 5 min to 20 min, it is passed through a TEVA resin column.

[0036] Further, in step S4, 5 to 20 column volumes of 8 mol / L nitric acid and 5 to 20 column volumes of 9 mol / L hydrochloric acid are used to elute the TEVA resin column, and then 5 to 20 column volumes of the third mixed acid are used to elute plutonium;

[0037] The concentration of hydrochloric acid in the third mixed acid is 0.1 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

[0038] The beneficial effects of the present invention are as follows: adopting a combined analysis method of uranium and plutonium isotopes in a water sample provided by the present invention, by enriching the uranium and plutonium isotopes in the water sample to be tested, a sample solution is obtained; the uranium and plutonium in the sample solution are separated by an anion exchange resin column to obtain a first uranium component and a first plutonium component respectively; the first uranium component is secondary purified by an anion exchange resin column to obtain a second uranium component and measure the content of uranium isotopes therein; the first plutonium component is secondary purified by a TEVA resin column to obtain a second plutonium component and measure the content of plutonium isotopes therein; it can be used to quickly and accurately determine and analyze the uranium and plutonium isotope contents in the sample at the same time to meet the needs of environmental monitoring, workplace radiation hazard characteristic assessment, dose assessment, and nuclear evidence collection. The separation process scheme provided by the present invention has a good separation effect on uranium and plutonium isotopes, and has a good decontamination effect on radioactive interfering nuclides such as thorium isotopes in the sample, and has a high chemical recovery rate and high analysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a process for the combined analysis of uranium and plutonium isotopes in a water sample provided by an embodiment of the present invention;

[0040] Figure 2 The separation and purification obtained by the embodiment of the present invention 232 α spectrum of U;

[0041] Figure 3 The separation and purification obtained by the embodiment of the present invention 242 Alpha spectrum of Pu. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention are further clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] In view of the need to simultaneously analyze uranium and plutonium isotopes in the same sample, an embodiment of the present invention proposes a method for the joint measurement of uranium and plutonium isotopes. After the sample is pretreated, it passes through an anion exchange resin, and the plutonium isotopes are retained on the resin column, and the uranium isotopes enter the effluent. The plutonium isotopes are purified by the anion exchange resin column and then further purified by the TEVA resin column. The uranium isotopes in the effluent are further purified by the anion exchange resin. The purified uranium and plutonium isotopes can be measured by an alpha spectrometer or an inductively coupled plasma mass spectrometer. This method has a strong ability to separate uranium and plutonium isotopes, a strong ability to decontaminate radioactive interfering nuclides in the sample, and a high chemical recovery rate and high analysis efficiency.

[0044] like Figure 1-3 As shown, this embodiment provides a method for joint analysis of uranium and plutonium isotopes in water samples, the method comprising the following steps:

[0045] S1. Enrich the uranium and plutonium isotopes in the water sample to be tested to obtain a sample solution;

[0046] The step S1 comprises the following specific steps: adding a known amount of 242 Pu, 232 U or 233 U standard solution is used as a tracer, the pH of the water sample to be tested is adjusted to less than 1, titanium trichloride (TiCl3) solution is added, and the pH of the water sample system is adjusted to 8-10 with ammonia water (NH3H2O), and it is fully shaken to generate a white first precipitate. The mixture is centrifuged and the supernatant is discarded, and the first precipitate is washed with high-purity water and the supernatant is discarded; the first precipitate is then dissolved with nitric acid, and sodium nitrite solution is added. After standing for a certain period of time, a sample solution is obtained.

[0047] Optionally, in step S1, hydrochloric acid or nitric acid is used to adjust the pH of the water sample to be tested to less than 1, so as to dissolve the uranium and plutonium isotopes in the water sample to be tested into the water.

[0048] Specifically, in step S1, the mass percentage of titanium trichloride in the titanium trichloride solution is 15%, and the volume ratio of the titanium trichloride solution to the water sample to be tested is 1:100 to 1:1000.

[0049] When the pH value of the water sample system is adjusted to 8-10 by ammonia water (NH3H2O), titanium trichloride (TiCl3) is hydrolyzed into HTiO. HTiO acts as a coprecipitant to remove the 242 Pu, 232 U is enriched in the first precipitate.

[0050] Optionally, in step S1, the first precipitate is dissolved with 8 mol / L nitric acid, 0.1 mL to 1 mL of 3 mol / L sodium nitrite solution is added, and the mixture is allowed to stand for 5 min to 20 min to obtain the sample solution.

[0051] S2, separating uranium and plutonium in the sample solution to obtain a first uranium component and a first plutonium component;

[0052] The step S2 comprises the following specific steps: passing the sample solution through an anion exchange resin column, eluting the anion exchange resin column with nitric acid and hydrochloric acid in sequence, and then eluting plutonium with a first mixed acid formed by mixing hydrochloric acid and hydrofluoric acid. The effluent of the sample solution passing through the anion exchange resin column is combined with the nitric acid eluent to obtain a first uranium component; the first mixed acid eluent is the first plutonium component.

[0053] Specifically, in step S2, the anion exchange resin column is eluted with 5 to 20 column volumes of 8 mol / L nitric acid and 5 to 20 column volumes of 9 mol / L hydrochloric acid in sequence.

[0054] Optionally, in step S2, plutonium is eluted using 5 to 20 column volumes of a first mixed acid, wherein the concentration of hydrochloric acid in the first mixed acid is 0.1 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

[0055] S3, purifying the first uranium component for a second time to obtain a second uranium component and measuring the 232 U content;

[0056] The step S3 comprises the following specific steps: adding titanium trichloride solution to the first uranium component, adjusting the pH value of the first uranium component system to 8-10 with ammonia water, shaking thoroughly, centrifuging and discarding the supernatant, washing the obtained second precipitate with high-purity water and discarding the supernatant, then dissolving the second precipitate with HCl, passing the dissolved solution through an anion exchange resin column, eluting the anion exchange resin column with HCl, and then eluting uranium with a second mixed acid mixed with nitric acid and hydrofluoric acid, and the obtained second mixed acid eluate is the second uranium component; measuring the second uranium component by using an α spectrometer or an inductively coupled plasma mass spectrometer 232 U content.

[0057] When an alpha spectrometer is used to measure the content of uranium isotopes in the second uranium component, the second uranium component is prepared as an alpha source by a microprecipitation method, and the alpha spectrum of the uranium isotopes therein is measured by an alpha spectrometer, and the content of the corresponding uranium isotope is obtained by alpha counting of characteristic energy peaks in the alpha spectrum of the uranium isotopes; when an inductively coupled plasma mass spectrometer is used to measure the content of uranium isotopes in the second uranium component, the content of the corresponding uranium isotope is obtained directly by measuring the number of ions of different uranium isotopes.

[0058] Specifically, in step S3, the mass percentage of titanium trichloride in the titanium trichloride solution is 15%, and the volume ratio of the titanium trichloride solution to the first uranium separation solution is 1:100 to 1:1000.

[0059] Optionally, in step S3, the second precipitate is dissolved with 6 mol / L HCl; the anion exchange resin column is eluted with 5 to 20 column volumes of 6 mol / L HCl, and then the uranium is eluted with 5 to 20 column volumes of a second mixed acid; the nitric acid concentration in the second mixed acid is 0.2 mol / L, and the hydrofluoric acid concentration is 0.05 mol / L.

[0060] S4, purifying the first plutonium component for a second time to obtain a second plutonium component and detecting the 242 Pu content;

[0061] The step S4 comprises the following specific steps: adding titanium trichloride solution to the first plutonium component, adjusting the pH value of the first plutonium component system to 8-10 with ammonia water, shaking thoroughly, centrifuging and discarding the supernatant, washing the obtained third precipitate with high-purity water and discarding the supernatant, then dissolving the third precipitate with nitric acid, adding sodium nitrite solution to the dissolving solution, passing through a TEVA resin column, eluting the TEVA resin column with nitric acid and hydrochloric acid in turn, and then eluting plutonium with a third mixed acid mixed with hydrochloric acid and hydrofluoric acid, and the obtained third mixed acid eluate is the second plutonium component; measuring the third precipitate with an α spectrometer or an inductively coupled plasma mass spectrometer 242 The content of Pu.

[0062] When the content of plutonium isotopes in the second plutonium component is measured by an α spectrometer, the second plutonium component is prepared as an α source by a microprecipitation method, and the α spectrum of the plutonium isotopes therein is measured by an α spectrometer, and the content of the corresponding plutonium isotope is obtained by counting the α counts of the characteristic energy peaks in the α spectrum of the plutonium isotopes; when the content of the plutonium isotopes in the second plutonium component is measured by an inductively coupled plasma mass spectrometer, the corresponding isotope is directly obtained by measuring the number of ions of different plutonium isotopes. 242 The content of Pu.

[0063] Specifically, in step S4, the mass percentage of titanium trichloride in the titanium trichloride solution is 15%, and the volume ratio of the titanium trichloride solution to the first uranium separation solution is 1:100 to 1:1000.

[0064] Optionally, in step S4, the third precipitate is dissolved with 8 mol / L nitric acid, 0.1 mL to 1 mL of 3 mol / L sodium nitrite solution is added, and after standing for 5 min to 20 min, it is passed through a TEVA resin column.

[0065] Optionally, in step S4, 5 to 20 column volumes of 8 mol / L nitric acid and 5 to 20 column volumes of 9 mol / L hydrochloric acid are used to elute the TEVA resin column in sequence, and then 5 to 20 column volumes of a third mixed acid are used to elute plutonium; the hydrochloric acid concentration in the third mixed acid is 0.1 mol / L, and the hydrofluoric acid concentration is 0.05 mol / L.

[0066] The specific implementation modes of the present invention are further described below through examples.

[0067] Example

[0068] use 242 Pu, 232 U standard solution represents uranium and plutonium isotopes. In a 50mL centrifuge tube, add 20mL of high-purity water, 24.9mBq 242 Pu, 29.8mBq 232U are mixed evenly to prepare a sample to be tested containing both uranium and plutonium isotopes. The method provided in this embodiment is used to separate and purify 242 Pu and 232 U, purified 242 Pu and 232 U was prepared as α source by microprecipitation method and measured by α spectrometer to verify the separation effect and recovery rate of uranium and plutonium provided by the method of this embodiment.

[0069] S11, enriching uranium and plutonium isotopes to obtain sample solution;

[0070] Add 0.17 mL of 12 mol / L HCl to the sample to be tested to adjust the pH of the sample system to <1, add 0.2 mL of 15% titanium trichloride, adjust the pH to 8-9 with concentrated ammonia water, shake thoroughly to generate a white first precipitate, centrifuge, discard the supernatant, wash the first precipitate with 10 mL of high-purity water, and discard the supernatant; then dissolve the first precipitate with 5 mL of 8 mol / L nitric acid, add 0.1 mL of 3 mol / L sodium nitrite solution thereto, and after standing for 10 minutes, obtain a sample solution.

[0071] S12, separating uranium and plutonium in the sample solution to obtain a first uranium component and a first plutonium component;

[0072] The sample solution was passed through a 0.5 mL AGMP-1 anion exchange resin column treated with 8 mol / L HNO3, and the effluent was collected in a 50 mL centrifuge bottle. The resin column was eluted with 5 mL 8 mol / L nitric acid and 5 mL 9 mol / L hydrochloric acid in turn, and then 5 mL of the first mixed acid (0.1 mol / L hydrochloric acid + 0.05 mol / L hydrofluoric acid) was used to elute plutonium. The effluent and the 8 mol / L nitric acid eluent were combined to obtain the first uranium component; the first mixed acid eluent was the first plutonium component.

[0073] S13, purifying the first uranium component for a second time to obtain a second uranium component and measuring the 232 α spectrum of U;

[0074] Add 0.2 mL of 15% titanium trichloride (TiCl3) solution to the first uranium component, adjust the system pH to 8-10 with ammonia water, shake thoroughly to generate a white second precipitate, centrifuge, discard the supernatant, wash the obtained second precipitate with high-purity water, discard the supernatant, dissolve the second precipitate with 5 mL of 6 mol / L HCl, pass through a 0.5 mL AGMP-1 anion exchange resin column treated with 6 mol / L HCl, elute the resin column with 5 mL of 6 mol / L HCl, and then elute the uranium with 5 mL of a second mixed acid prepared by mixing 0.2 mol / L nitric acid and 0.05 mol / L hydrogen fluoride. The obtained second mixed acid eluate is the second uranium component.

[0075] The second uranium component is prepared as an α source by a microprecipitation method, and an α spectrometer is used to measure the 232 The specific method of U activity is as follows: add 50 μL of 1 mg / mL cerium standard solution, 0.5 mL of 15% TiCl3 solution, and 1 mL of 40% hydrofluoric acid to the second uranium component, mix well, let stand for 10 minutes, filter through a filter membrane with a diameter of 20 mm and a pore size of 0.1 μm, wash the filter membrane with 5 mL of high-purity water and 5 mL of ethanol, remove the filter membrane and stick it on a round plastic sheet with a diameter of 20 mm with double-sided tape, as 232 U's α measurement source; measured using an α spectrometer 232 The α measurement source of U for 24 hours was obtained at 5263keV and 5320keV respectively. 232 The α count of U was measured by separation and purification. 232 The α spectrum of U is as follows Figure 2 shown.

[0076] S14, purifying the first plutonium component for a second time to obtain a second plutonium component and detecting the 242 α spectrum of Pu;

[0077] Add 0.2 mL of 15% titanium trichloride (TiCl3) solution to the first plutonium component, adjust the system pH to 8-10 with ammonia water, shake thoroughly to generate a white third precipitate, centrifuge, discard the supernatant, wash the third precipitate with 10 mL of high-purity water, discard the supernatant, dissolve the third precipitate with 8 mol / L nitric acid, add 0.1 mL of 3 mol / L sodium nitrite solution to the dissolving solution, let it stand for 10 min, pass through a 0.5 mL T EVA resin column treated with 8 mol / L nitric acid, elute the resin column with 5 mL of 8 mol / L nitric acid and 5 mL of 9 mol / L hydrochloric acid in turn, and then elute plutonium with 5 mL of the third mixed acid (0.1 mol / L hydrochloric acid + 0.05 mol / L hydrofluoric acid). The obtained third mixed acid eluate is the second plutonium component.

[0078] The second plutonium component is prepared as an α source by a microprecipitation method, and an α spectrometer is used to measure the 242 The specific method of Pu activity is as follows: add 50 μL of 1 mg / mL cerium standard solution, 0.5 mL of 15% TiCl3 solution, and 1 mL of 40% hydrofluoric acid to the second plutonium component, mix well, let stand for 10 minutes, filter through a filter membrane with a diameter of 20 mm and a pore size of 0.1 micron, wash the filter membrane with 5 mL of high-purity water and 5 mL of ethanol, and stick it on a round plastic sheet with a diameter of 20 mm with double-sided tape as a 242 The α measurement source of Pu was measured by an α spectrometer for 24 hours, and the values ​​were obtained at 4858.2keV and 4902.3keV respectively. 242 The α count of Pu was measured by separating and purifying 242 The α spectrum of Pu is as follows Figure 3shown.

[0079] S15, measurement result analysis: Since the present embodiment adopts 242 Pu, 232 U standard solution represents uranium and plutonium isotopes. 242 Pu, 232 U activity is a known quantity (24.9 mBq 242 Pu, 29.8mBq 232 U). The method provided in this embodiment is used to separate and purify the 232 U and 242 Pu, purified 232 U and 242 Pu was prepared as α source by microprecipitation method and measured by α spectrometer to obtain the corresponding 232 U's alpha count, 242 The α count of Pu is used to verify the separation effect and recovery rate of uranium and plutonium by the method provided in this embodiment.

[0080] Specifically, according to formula (1) and (2), the 242 Pu, 232 The recovery rate (R) and minimum detection limit (MDA) of U; the calculation results are shown in Table 1.

[0081]

[0082] Among them, R is 242 Pu or 232 U process recovery rate;

[0083] A2 is 242 Pu or 232 α spectrometer measurement value of U, mBq;

[0084] A1 is added 242 Pu or 232 U is the activity of the standard solution, mBq;

[0085] N is 242 Pu or 232 The count of U at its α characteristic energy;

[0086] t is the measurement time, s;

[0087] ε is the counting efficiency, which is taken as 23%.

[0088]

[0089] Among them, k is the inclusion factor, which is 1.645 (confidence level is 95%);

[0090] B is the blank sample when the α spectrometer is measuring242 Pu or 233 U corresponds to the count of energy values;

[0091] R is 242 Pu or 232 U process recovery rate;

[0092] ε is the counting efficiency, which is taken as 23%;

[0093] t is the measurement time, s.

[0094] Table 1 242 Pu 233 Recovery rate and minimum detection limit of U

[0095]

[0096] Figure 2 For separation and purification 232 U's α spectrum, Figure 3 For separation and purification 242 The α spectrum of Pu, as can be seen from the spectrum, after the combined separation process, 242 The α spectrum of Pu is 232 The counts at the α characteristic energy of U (5263kev, 5320kev) are not higher than the background value. 232 The α spectrum of U is 242 The counts at Pu's characteristic energies (4858.2kev, 4902.3kev) are no higher than the background value. 232 The radioactive daughters in equilibrium with the U standard solution 228 Th was added to the sample simultaneously. 228 The α characteristic energy of Th is (5340kev, 5423kev). 242 Pu and 232 On the α spectrum of U, 228 The counts at the α characteristic energy of Th are all lower than the background value. Therefore, the separation process has a good separation effect on uranium and plutonium isotopes and a good decontamination effect on thorium isotopes.

[0097] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these 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 also intended to include these modifications and variations.

Claims

1. A method for joint analysis of uranium and plutonium isotopes in water samples, characterized in that: The method comprises the following steps: S1. Enrich the uranium and plutonium isotopes in the water sample to be tested to obtain a sample solution; S2, separating uranium and plutonium in the sample solution by an anion exchange resin column to obtain a first uranium component and a first plutonium component, respectively; S3, performing secondary purification on the first uranium component through an anion exchange resin column to obtain a second uranium component and measuring the content of uranium isotopes therein; S4. Purify the first plutonium component for a second time through a TEVA resin column to obtain a second plutonium component and measure the plutonium isotope content therein.

2. The method for combined analysis of uranium and plutonium isotopes in water samples according to claim 1, characterized in that: Step S1 includes the following specific steps: Add a known amount of 242 Pu, 232 U or 233 U standard solution as tracer; Adjust the pH of the water sample to be tested to less than 1, add titanium trichloride solution, adjust the pH of the water sample system to 8-10 with ammonia water, shake thoroughly to generate a white first precipitate, centrifuge and discard the supernatant, wash the first precipitate with high-purity water and discard the supernatant; The first precipitate is then dissolved with nitric acid, and a sodium nitrite solution is added thereto, and after standing for a certain period of time, a sample solution is obtained.

3. The method for combined analysis of uranium and plutonium isotopes in water samples according to claim 2, characterized in that: In step S1, hydrochloric acid or nitric acid is used to adjust the pH of the water sample to less than 1.

4. The method for combined analysis of uranium and plutonium isotopes in water samples according to claim 2, characterized in that: In step S1, the mass percentage of titanium trichloride in the titanium trichloride solution is 15%, and the volume ratio of the titanium trichloride solution to the water sample to be tested is 1:100 to 1:1000.

5. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 2, characterized in that: In step S1, the first precipitate is dissolved with 8 mol / L nitric acid, 0.1 mL to 1 mL of 3 mol / L sodium nitrite solution is added, and the mixture is allowed to stand for 5 min to 20 min to obtain the sample solution.

6. The method for combined analysis of uranium and plutonium isotopes in water samples according to claim 1, characterized in that: Step S2 includes the following specific steps: Passing the sample solution through an anion exchange resin column, eluting the anion exchange resin column with nitric acid and hydrochloric acid in sequence, and then eluting plutonium with a first mixed acid formed by mixing hydrochloric acid and hydrofluoric acid; The effluent of the sample solution passing through the anion exchange resin column is combined with the nitric acid eluent to obtain the first uranium component; the first mixed acid eluent is the first plutonium component.

7. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 6, characterized in that: In step S2, the anion exchange resin column is eluted with 5 to 20 column volumes of 8 mol / L nitric acid and 5 to 20 column volumes of 9 mol / L hydrochloric acid in sequence.

8. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 6, characterized in that: In step S2, plutonium is eluted using 5 to 20 column volumes of a first mixed acid, wherein the concentration of hydrochloric acid in the first mixed acid is 0.1 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

9. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 1, characterized in that: Step S3 includes the following specific steps: adding titanium trichloride solution to the first uranium component, adjusting the pH value of the first uranium component system to 8-10 with ammonia water, centrifuging and discarding the supernatant, washing the obtained second precipitate with high-purity water and discarding the supernatant, then dissolving the second precipitate with HCl, passing the dissolved solution through an anion exchange resin column, eluting the anion exchange resin column with HCl, and then eluting uranium with a second mixed acid mixed with nitric acid and hydrofluoric acid, and the obtained second mixed acid eluate is the second uranium component; The content of uranium isotopes in the uranium is measured using an alpha spectrometer or an inductively coupled plasma mass spectrometer.

10. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 9, characterized in that: In step S3, when the content of uranium isotopes in the second uranium component is measured by using an α spectrometer, the second uranium component is prepared as an α source by a microprecipitation method, and the α spectrum of the uranium isotopes therein is measured by using an α spectrometer, and the content of the corresponding uranium isotope is obtained by α counting of characteristic energy peaks in the α spectrum of the uranium isotopes; When the content of uranium isotopes in the second uranium component is measured by using an inductively coupled plasma mass spectrometer, the content of the corresponding uranium isotopes is obtained by measuring the number of ions of different uranium isotopes.

11. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 9, characterized in that: In step S3, the second precipitate is dissolved with 6 mol / L HCl; The anion exchange resin column is eluted with 5 to 20 column volumes of 6 mol / L HCl, and then the uranium is eluted with 5 to 20 column volumes of a second mixed acid; The concentration of nitric acid in the second mixed acid is 0.2 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

12. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 1, characterized in that: Step S4 includes the following specific steps: Add titanium trichloride solution to the first plutonium component, adjust the pH value of the first plutonium component system to 8-10 with ammonia water, shake thoroughly, centrifuge and discard the supernatant, wash the obtained third precipitate with high-purity water and discard the supernatant, then dissolve the third precipitate with nitric acid, add sodium nitrite solution to the dissolving solution, pass through a TEVA resin column, elute the TEVA resin column with nitric acid and hydrochloric acid in turn, and then elute plutonium with a third mixed acid formed by a mixture of hydrochloric acid and hydrofluoric acid, and the obtained third mixed acid eluate is the second plutonium component; The plutonium isotope content is measured using an alpha spectrometer or an inductively coupled plasma mass spectrometer.

13. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 12, characterized in that: In step S4, when the content of plutonium isotopes in the second plutonium component is measured by using an alpha spectrometer, the second plutonium component is prepared as an alpha source by a microprecipitation method, and the alpha spectrum of the plutonium isotopes therein is measured by using an alpha spectrometer, and the content of the corresponding plutonium isotope is obtained by alpha counting of characteristic energy peaks in the alpha spectrum of the plutonium isotopes; When the content of plutonium isotopes in the second plutonium component is measured by using an inductively coupled plasma mass spectrometer, the content of the corresponding plutonium isotopes is obtained by measuring the number of ions of different plutonium isotopes.

14. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 12, characterized in that: In step S4, the third precipitate is dissolved with 8 mol / L nitric acid, 0.1 mL to 1 mL of 3 mol / L sodium nitrite solution is added, and after standing for 5 min to 20 min, it is passed through a TEVA resin column.

15. The method for joint analysis of uranium and plutonium isotopes in water samples according to claim 12, characterized in that: In step S4, the TEVA resin column is eluted with 5 to 20 column volumes of 8 mol / L nitric acid and 5 to 20 column volumes of 9 mol / L hydrochloric acid in sequence, and then plutonium is eluted with 5 to 20 column volumes of the third mixed acid; The concentration of hydrochloric acid in the third mixed acid is 0.1 mol / L, and the concentration of hydrofluoric acid is 0.05 mol / L.

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