Rapid analysis method for measuring content of impurity elements in uranium-plutonium product

Abstract

The invention discloses a rapid analysis method for measuring the content of impurity elements in a uranium-plutonium product, which comprises the following steps: S1, dissolving the uranium-plutonium product with acid, and fixing the volume to obtain a uranium-plutonium product solution; s2, establishing a working standard curve, judging whether the concentration of a to-be-detected element in the uranium-plutonium product solution is matched with the working standard curve of the element or not, if so, directly taking the uranium-plutonium product solution as a to-be-detected sample solution, and if not, taking a certain volume of the uranium-plutonium product solution and diluting the uranium-plutonium product solution by a certain multiple to prepare the to-be-detected sample solution; and S3, taking a certain volume of the to-be-tested sample solution, sending the to-be-tested sample solution to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing, and calculating the content of the impurity elements in the uranium-plutonium product according to a test result. Compared with the prior art, the method does not need an impurity element separation process, has the advantages of simplicity, accuracy, rapidness and the like, and has important significance on improving the technical level of uranium plutonium product impurity element content analysis.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear material element measurement, and in particular relates to a rapid analysis method for measuring the impurity element content of uranium-plutonium products. Background Art

[0002] Nuclear material uranium and plutonium products contain trace or trace amounts of impurity elements, including Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Mo, Pb, Li, B, Na, Sr, Ag, Sn, Sb, Ba, Bi, Be, Cd, Th, etc. The content of impurity elements is crucial to product quality control and product performance. Therefore, the analysis of the content of impurity elements in uranium and plutonium products is of great significance in nuclear material related processes and procedures.

[0003] At present, the nuclear industry uses inductively coupled plasma atomic emission spectrometry (ICP-OES) to determine the impurity elements in uranium and plutonium products (EJ / T 20163-0183). However, this method is complicated. Since the uranium and plutonium matrix content in nuclear material uranium and plutonium products is high and has large interference, the ICP-OES analysis of impurity elements with a low content (μg / g) requires the separation of impurity elements (including impurity element adsorption, desorption, column immersion and elution steps). The entire separation process takes a long time, is prone to certain measurement errors, and has high labor costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a rapid analysis method for measuring the impurity element content of uranium-plutonium products in view of the above-mentioned deficiencies in the prior art. Compared with the prior art, the present invention does not require the separation process of the impurity elements and has the advantages of being simple, accurate and rapid, which is of great significance for improving the technical level of the analysis of the impurity element content of uranium-plutonium products.

[0005] The technical solution of the present invention to solve the above technical problems is:

[0006] A rapid analytical method for measuring the content of impurity elements in uranium-plutonium products, comprising:

[0007] S1, dissolving the uranium-plutonium product with acid, and fixing the volume to obtain a uranium-plutonium product solution;

[0008] S2, establishing a working standard curve, judging whether the concentration of the element to be tested in the uranium-plutonium product solution is consistent with the working standard curve of the element, if it is consistent, directly using the uranium-plutonium product solution as the sample solution to be tested, if it is not consistent, taking a certain volume of the uranium-plutonium product solution and diluting it a certain multiple to prepare the sample solution to be tested;

[0009] S3, taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing, and calculating the impurity element content of the uranium-plutonium product based on the test results.

[0010] Optionally, the acid is 1.0-8.0 mol / L nitric acid.

[0011] Optionally, the fit means that the concentration of the element to be measured is within the concentration points of the working standard curve.

[0012] Optionally, the mismatch means that the concentration of the element to be measured is outside the concentration point of the working standard curve.

[0013] Optionally, the dilution uses ultrapure water as a diluent, and the concentration of the uranium-plutonium product solution after dilution is in the range of g / L to mg / L.

[0014] Optionally, the multiplex quality screening includes a first screening and a second screening.

[0015] Optionally, the multiple reaction modes include normal mode, cooling mode, and ammonia / helium / oxygen mode.

[0016] Optionally, taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing comprises the following steps:

[0017] First, set the theoretical mass number of the first screening according to the element to be measured;

[0018] Then, according to the type of element to be measured, set the appropriate reaction mode;

[0019] Then, according to the coupling between the element to be measured and the reaction gas, set the theoretical mass number for the second screening;

[0020] Finally, inject the sample and start the test.

[0021] Optionally, when the elements to be measured are B, Be, and Ag, the reaction mode is set to the normal mode.

[0022] Optionally, when the element to be measured is Li, Na, or Mg, the reaction mode is set to a cooling mode.

[0023] Optionally, when the element to be measured is Al, K, or Ca, the reaction mode is set to an ammonia mode.

[0024] Optionally, when the element to be measured is P, Ti, or V, the reaction mode is set to a helium / oxygen mode.

[0025] Beneficial effects:

[0026] The rapid analysis method for measuring the impurity element content of uranium-plutonium products of the present invention fully considers the characteristics of uranium-plutonium products, dissolves the uranium-plutonium product sample with nitric acid, dilutes it to a certain concentration, and directly uses an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for detection. Compared with the prior art, it does not need to undergo the pre-treatment operation of the impurity element separation process, and at least has the advantages of simplicity, accuracy, and rapidity, and is of great significance to improving the technical level of the impurity element content analysis of uranium-plutonium products. Specifically:

[0027] (1) The pretreatment operation involved in this method does not require the separation of impurity elements, and only involves dissolution and dilution operations. The pretreatment takes about 0.2 h, and the inductively coupled plasma mass spectrometer takes about 0.3 h to analyze multiple impurities (about 28 types). The entire impurity element analysis process (including pretreatment) is shortened to 0.5 h, which is fast and efficient.

[0028] (2) This method has high accuracy. Under repeatable conditions, the relative standard deviation of various impurity elements (Al, P, K, Ca, etc.) is better than 5%.

[0029] (3) This method saves equipment, devices, consumables and manpower for separation operations, and can significantly save the construction and operation costs of the analysis of impurity element content in uranium and plutonium products.

[0030] (4) It can be expanded to many scenarios, which is beneficial to radiation protection. For example, the inductively coupled plasma mass spectrometer can be combined with a glove box to achieve effective biological shielding and glove box radioactive containment functions, and can adapt to uranium-plutonium products and a variety of uranium-plutonium-containing radioactive liquids. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a flow chart of a rapid analysis method for measuring the impurity element content of uranium and plutonium products according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0033] In view of the fact that the method for measuring the impurity element content of uranium-plutonium products in the prior art requires the separation of impurity elements, which has the problems of long time, easy measurement errors and high labor costs, the present invention discloses a rapid analysis method for measuring the impurity element content of uranium-plutonium products, comprising:

[0034] S1, dissolving the uranium-plutonium product with acid, and fixing the volume to obtain a uranium-plutonium product solution;

[0035] S2, establish a working standard curve to determine whether the concentration of the element to be measured in the uranium-plutonium product solution is consistent with the working standard curve of the element.

[0036] If they match, the uranium-plutonium product solution is directly used as the sample solution to be tested.

[0037] If they do not match, take a certain volume of uranium-plutonium product solution and dilute it a certain multiple to prepare the sample solution to be tested;

[0038] S3, taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing, and calculating the impurity element content of the uranium-plutonium product based on the test results.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment discloses a method for measuring the content of impurity elements in uranium and plutonium products, comprising:

[0041] S1, dissolving the uranium-plutonium product with acid and fixing the volume (V0) to obtain a uranium-plutonium product solution.

[0042] In this embodiment, the mass m0 of the uranium-plutonium product is 100 mg-3000 mg. The acid is 1.0-8.0 mol / L nitric acid, and the dissolution can make the sample evenly distributed in the solution, which is convenient for dilution and injection in the subsequent steps.

[0043] S2, establish a working standard curve to determine whether the concentration of the element to be measured in the uranium-plutonium product solution is consistent with the working standard curve of the element, wherein:

[0044] If the match is found, the uranium-plutonium product solution is directly used as the sample solution to be tested (V i ), that is, it can be injected directly without dilution;

[0045] If not, take a certain volume (V1) of uranium-plutonium product solution and dilute it a certain multiple to prepare the sample solution to be tested (V i ) and then inject the sample.

[0046] Among them, the working standard curve is established by the standard addition method. After taking an appropriate amount of uranium-plutonium product solution in S1 and diluting it appropriately, 100 μg / L mixed impurity element standard reagent (including 28 elements such as Mg, Al, P, etc.) is added by the standard addition method to prepare standard working points of 0.1, 0.5, 1, 2, 5, and 10 μg / L. The standard working points are tested on the machine to obtain the test data of the standard working points and perform linear fitting. When the regression coefficient of the fitting function is greater than 0.999, it can be used as the working standard curve to be used. If the regression coefficient is not satisfied, the standard working points are reconfigured and a new working standard curve is established until the requirements are met.

[0047] Among them, the concentration range composed of the standard working points should include the theoretical concentration of the sample solution to be tested.

[0048] Among them, match means that the concentration of the element to be measured is within the concentration points of the working standard curve; mismatch means that the concentration of the element to be measured is outside the concentration points of the working standard curve. At this time, the concentration of the element to be measured is too different from the working standard curve of the element. By selecting the dilution multiple to perform the dilution operation, samples can be saved and injection can be facilitated.

[0049] In this embodiment, ultrapure water is used as a diluent for dilution. The concentration of the uranium-plutonium product solution after dilution is in the range of g / L to mg / L to ensure that the concentration of the element to be measured in the sample solution is within the concentration point of its working standard curve, so that it is possible to avoid the concentration being too large (above the g / L level) and seriously contaminating the pipeline, atomizer, interceptor cone and extraction cone of the subsequent test instrument, and the introduction of a mass analyzer will lead to serious matrix effects such as suppression of element signals, and produce a very high background value that will prevent and limit element analysis in subsequent steps, and it is possible to avoid the impurity element content being often lower than the ppt level when the concentration is too low (such as U / Pu elements below the mg / L level) and thus being difficult to detect.

[0050] S3, taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer (ICP-MS) with multiple mass screening and multiple reaction modes for testing, and calculating the impurity element content of the uranium-plutonium product based on the test results.

[0051] Specifically, multiple mass screening means that the inductively coupled plasma mass spectrometer includes at least a first screening and a second screening for setting the theoretical mass number of the element to be measured, wherein the theoretical mass number of the first screening is selected and set according to the element to be measured, and the theoretical mass number of the second screening is selected and set according to the coupling between the element to be measured and the reaction gas in the selected reaction mode.

[0052] Multiple reaction modes mean that the inductively coupled plasma mass spectrometer includes at least normal mode (NO GAS), cooling mode (also called cold plasma mode (COOL)), ammonia (NH3) / helium (He) / oxygen (O2) mode and other measurement modes. It can also be any combination of multiple measurement modes, for example, hydrogen helium (H2 / He), ammonia helium (NH3 / He), etc., to ensure accurate removal of interfering ions.

[0053] Specifically, the specific analysis process of the sample of this method in the inductively coupled plasma mass spectrometer is as follows: ① After the sample solution to be tested is injected, it is first ionized in the ICP source, and then the theoretical mass number of the ions is screened for the first time; ② The screened ions enter the reaction cell, where the ions can react with a variety of gases, such as ammonia, oxygen, helium, etc., which is determined by the selected test mode, thereby causing the mass of the ions to change; ③ The theoretical mass number of the ions is screened for a second time based on the theoretical ion mass after the reaction.

[0054] Compared with conventional inductively coupled plasma mass spectrometers, this method can effectively reduce the polyatomic ion interference caused by plasma gas, air, reagents and complex matrices by adopting an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes.

[0055] In some embodiments, the step of taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing includes:

[0056] First, set the theoretical mass number of the first screening according to the element to be tested. For example, when the element to be tested is P, the theoretical mass number of the first screening can be set to 31.

[0057] Then, according to the type of element to be tested, set the appropriate reaction mode. For example, when the element to be tested is P31, the O2 mode can be selected. Compared with other modes, this mode can eliminate the interference of NOH, SiO and NO.

[0058] Then, according to the coupling between the element to be measured and the reaction gas, set the theoretical mass number of the second screening. For example, after P31 selects the O2 mode, the theoretical mass number of the second setting can be set to 47 (considering that the product is PO);

[0059] Finally, inject the sample, start the test, and get the test results.

[0060] In this embodiment, the impurity element content of the uranium-plutonium product is calculated according to the test results, specifically, the mass fraction of a certain impurity to be measured in the uranium-plutonium product is calculated according to the following formula:

[0061]

[0062] Among them, ρ i is the mass concentration of impurity elements tested by inductively coupled plasma mass spectrometry, i is the element symbol, which can be 28 elements such as Mg, Al, P, etc.; V0 is the constant volume of uranium-plutonium product after the first dissolution, that is, Figure 1 V1 is the volume of the uranium-plutonium product solution to be diluted; V2 is the volume of the first constant volume dissolution, that is, the volume of the uranium-plutonium product solution used for dilution; V i is the second volume after dilution, i.e. the volume of the sample solution to be tested after dilution by a certain multiple; m0 is the mass of the dissolved solid uranium-plutonium product; i represents the impurity element (Al, P, K, Ca, etc.). If the solid uranium-plutonium product is dissolved and then sampled directly, V0 = V1 = V i .

[0063] In some embodiments, when the element to be measured is B, Be, or Ag, the reaction mode is set to a normal mode; when the element to be measured is Li, Na, or Mg, the reaction mode is set to a cooling mode; when the element to be measured is Al, K, or Ca, the reaction mode is set to an ammonia mode. When the element to be measured is P, Ti, or V, the reaction mode is set to a helium / oxygen mode.

[0064] The rapid analysis method for measuring the impurity element content of uranium-plutonium products of this embodiment fully considers the characteristics of uranium-plutonium products. The uranium-plutonium product sample is dissolved by nitric acid and diluted to a certain concentration, and is directly detected by an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes. Compared with the prior art, it does not need to undergo the pre-treatment operation of the impurity element separation process, and at least has the advantages of simplicity, accuracy, and speed, which is of great significance to improving the technical level of the impurity element content analysis of uranium-plutonium products. Specifically:

[0065] (1) The pretreatment operation involved in this method does not require the separation of impurity elements, and only involves dissolution and dilution operations. The pretreatment takes about 0.2 h, and the inductively coupled plasma mass spectrometer takes about 0.3 h to analyze multiple impurities (about 28 types). The entire impurity element analysis process (including pretreatment) is shortened to 0.5 h, which is fast and efficient.

[0066] (2) This method has high accuracy. Under repeatable conditions, the relative standard deviation of various impurity elements (Al, P, K, Ca, etc.) is better than 5%.

[0067] (3) This method saves equipment, devices, consumables and manpower for separation operations, and can significantly save the construction and operation costs of the analysis of impurity element content in uranium and plutonium products.

[0068] (4) It can be expanded to many scenarios, which is beneficial to radiation protection. For example, the inductively coupled plasma mass spectrometer can be combined with a glove box to achieve effective biological shielding and glove box radioactive containment functions, and can adapt to uranium-plutonium products and a variety of uranium-plutonium-containing radioactive liquids.

[0069] Example 2

[0070] like Figure 1 As shown, this embodiment discloses a rapid analysis method for measuring the impurity element content of uranium-plutonium products, which is different from embodiment 1 in that the steps are as follows:

[0071] S1, dissolving the uranium-plutonium product with acid, fixing the volume, and obtaining a uranium-plutonium product solution.

[0072] Specifically, the steps include: first, weighing the uranium-plutonium product: using an electronic analytical balance to weigh 500 mg (accurate to 0.1 mg) of solid uranium-plutonium product into a quartz crucible;

[0073] Then, perform preliminary dissolution: slowly add 2 mL of nitric acid (5 mol / L) along the wall, cover and heat on a hot plate to completely dissolve the uranium-plutonium product, evaporate to near dryness, and cool to room temperature;

[0074] Then, dissolve again: slowly add 1 mL of nitric acid (5 mol / L) along the wall to fully dissolve the uranium-plutonium product to obtain a uranium-plutonium product solution to be diluted;

[0075] Finally, adjust the volume: pour the uranium-plutonium product solution to be diluted into a 500mL volumetric flask made of perfluoroalkyl compound or polytetrafluoroethylene, rinse the quartz crucible several times with a small amount of ultrapure water and pour it into the volumetric flask, then add ultrapure water to adjust the volume to obtain the uranium-plutonium product solution (V0).

[0076] S2, establishing a working standard curve to determine whether the concentration of the element to be measured in the uranium-plutonium product solution is consistent with the working standard curve of the element.

[0077] Specifically, a working standard curve is established: after an appropriate amount of uranium-plutonium product solution in S1 is diluted appropriately, 100 μg / L of mixed impurity element standard reagent (including 28 elements such as Mg, Al, P, etc.) is added by the standard addition method to prepare standard working points of 0.5, 1, 2, 5, and 10 μg / L. The standard working points are tested on a machine to obtain the test data of the standard working points and perform linear fitting. When the regression coefficient of the fitting function is greater than 0.999, it can be used as the working standard curve to be used.

[0078] Among them, the concentration range composed of the standard working points should include the theoretical concentration of the sample solution to be tested.

[0079] If the match is found, the uranium-plutonium product solution is directly used as the sample solution to be tested (V i), that is, it can be injected directly without dilution;

[0080] If not, take a certain volume (V1) of uranium-plutonium product solution and dilute it a certain multiple to prepare the sample solution to be tested (V i ), and then inject the sample; or adjust the configuration points of the standard solution to re-create a working standard curve that adapts to the target concentration.

[0081] Among them, taking P and Ca as examples of impurity elements, the fitting curve of P at the above five standard working points is y=0.9198x+0.1332, and its regression coefficient R 2 =0.9998>0.999, the curve fitted by Ca at the above five standard working points is y=0.9556x+0.0721, and its regression coefficient R 2 =0.9999>0.999. At this time, the concentrations of P and Ca element impurities in the uranium-plutonium product solution are both greater than the range of the standard working point, that is, they do not meet the standard, so further dilution operation is required.

[0082] Dilution: Take 5mL (V1) of the above uranium-plutonium production solution into a 100mL volumetric flask, and add ultrapure water to make up to volume (Vi). At this time, the predicted P element concentration of the sample solution to be tested is within the working standard point, so it can be used as the sample solution to be tested.

[0083] S3, take a certain volume of the sample solution to be tested and send it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing, and calculate the impurity element content of the uranium-plutonium product based on the test results

[0084] Specifically, first, adjust the instrument status: use tuning fluid to calibrate the parameters of the inductively coupled plasma mass spectrometer (power, auxiliary gas flow, nebulizer gas flow, compensation gas flow, torque tube depth, nebulizer chamber temperature, reaction gas flow rate, etc.), and complete the record;

[0085] Then, select the test conditions and set the parameters of the elements to be tested. Take P and Ca elements as examples: set the theoretical mass number of the first screening of P to 31, set the measurement mode to O2 mode, and then the theoretical mass number of the second setting of P can be set to 47 (considering that the product is PO). P reacts with O2, and the target mass number changes to exclude the interference of NOH, SiO and NO; set the theoretical mass number of the first screening of Ca to 40, set the measurement mode to NH3 mode, and then the theoretical mass number of the second setting of Ca can be set to 40, where NH3 can form stable polyatomic ions with interfering ions (Ar, K, MgO) to change the mass number of the interfering ions.

[0086] Finally, the sample is injected for testing and the mass fractions of P and Ca in the uranium-plutonium products are calculated.

[0087] Using the above method, the mass fraction of impurity elements in uranium-plutonium products was determined six times under repeatable conditions (taking P and Ca in uranium products as an example).

[0088] Table 1

[0089] <![CDATA[W P ]]> <![CDATA[W Ca ]]> first 0.00003260 0.0001049 Second time 0.00003264 0.0001113 The third time 0.00003204 0.0001103 Fourth 0.000032645 0.0001100 Fifth 0.00003123 0.0001098 Sixth 0.00003087 0.0001067 RSD 2.44％ 2.26％

[0090] As can be seen from Table 1, the relative standard deviation RSD of the mass fraction of impurity elements in uranium-plutonium products determined by this method is less than 5%, which is better than the requirement of the original standard EJ / T 20163-0183 that the relative standard deviation is less than 15%, can meet the needs of engineering applications, and has the advantages of fast, accurate and efficient.

[0091] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A rapid analytical method for measuring the content of impurity elements in uranium and plutonium products, characterized in that: include: S1, dissolving the uranium-plutonium product with acid, and fixing the volume to obtain a uranium-plutonium product solution; S2, establish a working standard curve to determine whether the concentration of the element to be measured in the uranium-plutonium product solution is consistent with the working standard curve of the element. If they match, the uranium-plutonium product solution is directly used as the sample solution to be tested. If they do not match, take a certain volume of uranium-plutonium product solution and dilute it a certain multiple to prepare the sample solution to be tested; S3, taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing, and calculating the impurity element content of the uranium-plutonium product based on the test results.

2. The rapid analytical method for measuring the impurity element content of uranium-plutonium products according to claim 1 is characterized in that: The acid is 1.0-8.0 mol / L nitric acid.

3. The rapid analysis method for measuring the impurity element content of uranium-plutonium products according to claim 1 is characterized in that: The fit means that the concentration of the element to be measured is within the concentration points of the working standard curve; The mismatch means that the concentration of the element to be measured is outside the concentration point of the working standard curve.

4. The rapid analytical method for measuring the impurity element content of uranium-plutonium products according to claim 1, characterized in that: The dilution uses ultrapure water as a diluent, and the concentration of the uranium-plutonium product solution after dilution is in the range of g / L to mg / L.

5. The rapid analysis method for measuring the impurity element content of uranium-plutonium products according to claim 1 is characterized in that: The multiple quality screening includes a first screening and a second screening; The multiple reaction modes include normal mode, cooling mode, and ammonia / helium / oxygen mode; The steps of taking a certain volume of the sample solution to be tested and sending it to an inductively coupled plasma mass spectrometer with multiple mass screening and multiple reaction modes for testing include: First, set the theoretical mass number of the first screening according to the element to be measured; Then, according to the type of element to be measured, set the appropriate reaction mode; Then, according to the coupling between the element to be measured and the reaction gas, set the theoretical mass number for the second screening; Finally, inject the sample and start the test.

6. The rapid analysis method for measuring the impurity element content of uranium and plutonium products according to claim 5 is characterized in that: When the elements to be measured are B, Be, and Ag, set the reaction mode to normal mode; When the elements to be measured are Li, Na, and Mg, set the reaction mode to cooling mode; When the elements to be measured are Al, K, and Ca, set the reaction mode to ammonia mode; When the elements to be measured are P, Ti, and V, set the reaction mode to helium / oxygen mode.

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