Method for measuring content of silver in boron-containing water

Abstract

The invention provides a method for measuring silver content in boron-containing water, which comprises the following steps: preparing a blank standard solution and a standard working solution by using a first-stage diluent and a second-stage diluent, and respectively pretreating the blank standard solution, the standard working solution and a to-be-measured sample solution by using a third-stage diluent; the first-stage diluent comprises a nitric acid solution, the second-stage diluent comprises a boron solution, and the third-stage diluent comprises a nitric acid solution; and measuring the silver content of the to-be-measured sample solution by adopting inductively coupled plasma emission spectrometry. According to the determination method provided by the invention, the silver content in the boron-containing water of the nuclear power plant can be accurately and rapidly detected through pretreatment of the test solution, the problem of boron interference in the boron-containing water is solved, the detection accuracy of the silver content is improved, and support is provided for chemical control of nuclear power loop water.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and testing, and relates to a method for determining the silver content, in particular to a method for determining the silver content in boron-containing water. Background Art

[0002] Nuclear power plants use nuclear energy to produce electricity. Nuclear fuel undergoes fission in the reactor to generate a large amount of heat energy, which is then taken out by high-pressure water to generate steam in the steam generator. The steam drives the steam turbine to drive the generator to generate electricity. A pressurized water reactor nuclear power plant is mainly composed of a pressurized water reactor, a reactor coolant system (referred to as the primary circuit), a steam and power conversion system (also known as the secondary circuit), a circulating water system, a generator, and a power transmission and distribution system and its auxiliary systems.

[0003] When silver is introduced into the primary circuit of a nuclear power plant, the metastable isotope Ag-110m is generated under neutron irradiation. Ag-110m can quickly reach a high radioactivity and has a high activity-dose conversion coefficient ratio, which has a greater impact on the system's radioactivity.

[0004] During the overhaul of nuclear power units, when the primary loop is oxidizing and unloading, the high activity of radioactive silver in the water of the primary loop and its auxiliary systems will increase the radioactive dose of the workers and have an adverse effect on the overall dose control of the overhaul. The form of radioactive silver is closely related to the temperature, pH, redox properties and radiation field. Its existence form is uncertain, and it has the characteristics of low removal efficiency, easy activation, large solubility changes, and easy deposition, which brings great challenges to the discharge of radioactive waste liquid and overhaul dose control.

[0005] Therefore, tracking and detecting silver in nuclear power circuit water from a chemical perspective will help solve the problem of high radioactive silver activity and provide support for chemical control during subsequent unit overhaul oxidation operation and unloading.

[0006] Inductively coupled plasma emission spectrometry has the characteristics of high analytical precision, wide sample range, wide dynamic linear range, and high accuracy, and is widely used for element content determination. However, the result analysis of inductively coupled plasma emission spectrometry relies on element signal spectral lines, and spectral line overlap and background interference can easily cause deviations in the measurement results. The boron concentration in the primary loop water of a pressurized water reactor nuclear power plant ranges from tens of mg / L to more than 2,000 mg / L, which is much higher than the silver content. Boron will produce strong background interference in the determination of silver content, seriously interfering with the accurate measurement of silver.

[0007] In order to improve the chemical control of the unit, it is necessary to provide a method for determining the dissolved silver and total silver content in boron-containing water in nuclear power plants with fast analysis speed and high measurement accuracy. Summary of the invention

[0008] The purpose of the present invention is to provide a method for determining the silver content in boron-containing water, so as to solve the interference of high boron content in the loop water of nuclear power plants on the determination of silver, improve the determination efficiency and accuracy, and provide support for the chemical control of water used in nuclear power plants.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for determining the silver content in boron-containing water, the method comprising the following steps:

[0011] (1) preparing a blank standard solution and a standard working solution using a primary diluent and a secondary diluent, and pretreating the blank standard solution, the standard working solution and the sample solution using a tertiary diluent;

[0012] The primary diluent includes a nitric acid solution, the secondary diluent includes a boron solution, and the tertiary diluent includes a nitric acid solution;

[0013] (2) The silver content of the sample solution was determined by inductively coupled plasma emission spectrometry.

[0014] The determination method provided by the present invention adopts three-level diluents to prepare and process the determination test solution, wherein a nitric acid solution is selected as the first-level diluent to prepare a silver reserve standard solution, thereby improving the stability of the solution; a boron solution is selected as the second-level diluent to prepare a blank standard solution and a standard working solution, thereby effectively solving the problem of boron interference in boron-containing water during determination; and a nitric acid solution is selected as the third-level diluent to perform the same pretreatment on the blank solution, the standard solution and the sample to be measured, thereby converting the solid metallic silver in the sample to be measured into an ionic state, thereby reducing the error caused by the pretreatment and improving the accuracy of the determination.

[0015] Preferably, the boron concentration in the boron-containing water during the primary power operation of the nuclear power plant is 20-1500 mg / L, for example, it can be 20 mg / L, 50 mg / L, 100 mg / L, 300 mg / L, 500 mg / L, 800 mg / L, 1000 mg / L, 1200 mg / L or 1500 mg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the boron concentration in the boron-containing water during the period from shutdown of the primary circuit overhaul unit of a nuclear power plant to primary circuit oxidation operation and filling of the refueling pool is 1500-2700 mg / L, for example, it can be 1500 mg / L, 1800 mg / L, 2000 mg / L, 2200 mg / L, 2500 mg / L or 2700 mg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0017] Preferably, in the primary dilution solution of step (1), the volume ratio of nitric acid to water is (0.5-1.5):99, for example, it can be 0.5:99, 0.8:99, 0.9:99, 1:99, 1.1:99, 1.2:99 or 1.5:99, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, in the secondary dilution solution of step (1), the concentration of boron is 1000-2000 mg / L, for example, it can be 1000 mg / L, 1200 mg / L, 1500 mg / L, 1800 mg / L or 2000 mg / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, when the sample solution to be tested is water used during a single-loop oxidation operation and / or filling and refueling of a refueling pool, the boron concentration of the secondary dilution solution is 1900-2000 mg / L, for example, it can be 1900 mg / L, 1920 mg / L, 1950 mg / L, 1980 mg / L or 2000 mg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0020] Preferably, when the sample solution to be tested is water used during the operation of a primary circuit power, the boron concentration of the secondary dilution solution is 1000-1100 mg / L, for example, it can be 1000 mg / L, 1020 mg / L, 1050 mg / L, 1080 mg / L or 1100 mg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, in the tertiary dilution solution of step (1), the volume ratio of nitric acid to water is (0.8-1.2):1, for example, it can be 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the method for preparing the standard working solution in step (1) comprises: mixing the silver standard solution with the primary diluent to obtain a silver reserve standard solution, and diluting the silver reserve standard solution with the secondary diluent to obtain silver standard working solutions of different concentrations.

[0023] Preferably, the blank standard solution in step (1) is a secondary dilution solution.

[0024] Preferably, the dosage of the tertiary dilution solution in step (1) is (1.5-2.5) mL / 50 mL of solution, for example, it can be 1.5 mL / 50 mL, 1.8 mL / 50 mL, 1.9 mL / 50 mL, 2 mL / 50 mL, 2.1 mL / 50 mL, 2.2 mL / 50 mL or 2.5 mL / 50 mL, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the determination method further comprises: when determining the dissolved silver content, filtering the boron-containing water from the nuclear power plant using a filter membrane below 0.45 μm to obtain a sample solution to be tested.

[0026] In the present invention, the silver in the loop water of the pressurized water reactor nuclear power plant exists in the form of ions, insoluble solid and colloidal forms. The silver exists in the form of the system temperature, pH, redox properties and radiation field. When the boron-containing water is filtered, the insoluble solid silver in the water is separated, and the silver measured is the content of dissolved silver in the boron-containing water; when the boron-containing water is not filtered, the silver measured is the content of total silver in the boron-containing water.

[0027] Preferably, in step (2), the silver content of the sample solution to be tested is determined by inductively coupled plasma emission spectrometry, using an inductively coupled plasma emission spectrometer, and the determination process includes:

[0028] (a) Perform background correction of inductively coupled plasma emission spectroscopy;

[0029] (b) using the pretreated blank standard solution and the standard working solution to draw a standard working curve;

[0030] (c) The pretreated sample solution is measured to calculate the silver content.

[0031] Preferably, the background correction method in step (a) comprises: fixing the spectral signal at the positions where the boron interference is minimum on both sides of the silver analysis line as the left background and the right background, respectively.

[0032] The “position where boron interference is minimal” specifically refers to the spectral line position where the spectral signal intensity of blank standard solutions with different boron concentrations changes minimally.

[0033] The method for determining the "point with the minimum boron interference" includes: measuring a series of blank standard solutions containing different boron concentrations, superimposing and comparing the spectral curves, and selecting the position where the spectral curve changes the least with the boron concentration, which is the point with the minimum boron interference.

[0034] Preferably, the left background is 328.052 nm, and the right background is 328.085 nm.

[0035] Preferably, the calculation formula of the silver content in step (c) is as follows:

[0036] C=(Sa) / b

[0037] Wherein, C is the silver content in the sample, S is the peak signal value of the sample after silver correction, a is the intercept of the silver standard curve, and b is the slope of the silver standard curve.

[0038] Preferably, the nebulizer gas flow rate of the inductively coupled plasma emission spectrometer is 0.4-0.6 L / min, for example, it can be 0.4 L / min, 0.45 L / min, 0.5 L / min, 0.55 L / min or 0.6 L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the cooling gas flow rate of the inductively coupled plasma emission spectrometer is 10-15 L / min, for example, it can be 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min or 15 L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the auxiliary gas flow rate of the inductively coupled plasma emission spectrometer is 0.4-0.6 L / min, 0.4 L / min, 0.45 L / min, 0.5 L / min, 0.55 L / min or 0.6 L / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] Preferably, the analysis spectrum line of the inductively coupled plasma optical emission spectrometer is 328.068 nm.

[0042] Preferably, the RF generator power of the inductively coupled plasma emission spectrometer is 1100-1200 W, for example, it can be 1100 W, 1120 W, 1140 W, 1150 W, 1160 W, 1180 W or 1200 W, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] Preferably, the exposure time of the inductively coupled plasma emission spectrometer is 8-12 s, for example, 8 s, 9 s, 10 s, 11 s or 12 s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, the pump speed of the inductively coupled plasma emission spectrometer is 45-55RPM, for example, 45RPM, 48RPM, 50RPM, 52RPM or 55RPM, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Preferably, the injection delay of the inductively coupled plasma emission spectrometer is 25-35s, for example, it can be 25s, 28s, 30s, 32s or 35s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The determination method provided by the present invention can realize accurate and rapid detection of the silver content in boron-containing water of a nuclear power plant by pre-treating the test solution used, thereby solving the problem of boron interference therein, improving the detection accuracy of the silver content, and providing support for the chemical control of nuclear power loop water. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is an inductively coupled plasma emission spectrogram of a blank standard solution of the method for determining the silver content in boron-containing water provided in Example 1;

[0049] Figure 2 It is an inductively coupled plasma emission spectrum background correction diagram of a blank standard solution of the method for determining the silver content in boron-containing water provided in Example 1;

[0050] Figure 3 is an inductively coupled plasma emission spectrogram of a standard solution for the method for determining the silver content in boron-containing water provided in Example 1;

[0051] Figure 4 is the standard working curve of the method for determining the silver content in boron-containing water provided in Example 1;

[0052] Figure 5 is the standard working curve of the method for determining the silver content in boron-containing water provided in Example 2;

[0053] Figure 6 is a spectrum curve diagram of the automatic background of the background correction provided in Example 1;

[0054] Figure 7 This is a spectral curve diagram of the corrected background of the background correction provided in Example 1. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0056] In order to clearly illustrate the technical solution of the present invention, in a specific implementation manner, the inductively coupled plasma optical emission spectrometer used is a Thermofisher iCAP 7400 inductively coupled plasma optical emission spectrometer.

[0057] Example 1

[0058] This embodiment provides a method for determining the silver content in boron-containing water, and determines the dissolved silver content in the water used for primary oxidation operation in a pressurized water reactor nuclear power plant. The boron content in the water used for primary oxidation operation in the pressurized water reactor nuclear power plant is 2544 mg / L.

[0059] The determination method comprises the following steps:

[0060] (1) Preparation of dilution solution:

[0061] The three-level diluent includes: a primary diluent, a secondary diluent, and a tertiary diluent.

[0062] The first-level dilution solution is 1+99 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:99.

[0063] The secondary dilution solution is a boric acid solution with a boron concentration of 2000 mg / L.

[0064] The tertiary dilution solution is a 1+1 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:1.

[0065] The nitric acid used was Merck ultrapure nitric acid with a mass fraction of 65%.

[0066] The boric acid used was Merck high-purity boric acid with a purity of 99.9999%.

[0067] (2) Prepare blank standard solution, which is the secondary dilution solution.

[0068] (3) Preparation of standard solution:

[0069] A silver standard solution was selected, the silver standard solution was the silver standard solution of the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, the national standard sample number was GSB04-1712-2004, the concentration was 1000 mg / L, the relative expanded uncertainty Ur / % (k=2) was 0.7, and it was stored at room temperature away from light.

[0070] The silver standard solution was mixed with the primary diluent to dilute the silver standard solution to 1 mg / L to obtain a silver stock standard solution.

[0071] The silver stock standard solution was diluted with the secondary diluent to obtain standard solutions with silver concentrations of 20 μg / L, 50 μg / L, 100 μg / L and 200 μg / L, respectively.

[0072] (3) Prepare a sample solution to be tested. Filter the primary loop oxidation operating water of the pressurized water reactor nuclear power plant to be tested through a 0.45 μm filter membrane to obtain a sample solution to be tested.

[0073] (4) Test solution pretreatment:

[0074] Add the tertiary diluent to the blank standard solution, standard solution and sample solution in the same proportion, with the addition ratio of 2 mL of the tertiary diluent to every 50 mL of solution, to obtain the blank standard solution, standard solution and sample solution for testing.

[0075] (5) Perform background correction:

[0076] The blank standard solution after pretreatment is introduced into the inductively coupled plasma emission spectrometer for testing to obtain a signal spectrum, such as Figure 1 As shown, the instrument automatically selects the left background as 328.038nm and the right background as 328.092nm. The signal bulges at the two spectral lines are caused by the interference caused by boron, which will cause the peak signal of silver to appear negative after correction. Therefore, background correction is performed on the spectral lines.

[0077] The method for background correction includes: respectively measuring the spectral curves of blank standard solutions with boron concentrations of 500 mg / L, 1000 mg / L, 1500 mg / L, 2000 mg / L, 2500 mg / L, 3000 mg / L, 4000 mg / L and 5000 mg / L, superimposing and comparing the spectral curves, and determining the position where the spectral curve changes the least with boron concentration, which is determined as the position where boron interference is minimal, that is, the corrected left and right backgrounds, and the left and right backgrounds are 328.052 nm and 328.085 nm, respectively.

[0078] like Figure 6 As shown in the figure, the spectral line signals at the left and right backgrounds automatically selected by the instrument increase significantly with the increase of boron concentration, thus causing great interference to the measurement of Ag; Figure 7 As shown in the figure, the left and right backgrounds after correction are 328.052nm and 328.085nm respectively, which effectively reduces the interference of boron. The intensity changes of the left and right backgrounds before and after correction are shown in the following table.

[0079]

[0080] After correcting the left and right backgrounds, the corrected peak signal of silver increased from -79.35 to 8.17. The corrected peak signal was positive and had a good linear relationship.

[0081] (6) Draw the working curve:

[0082] After fixing the left and right backgrounds, the blank standard solution and the standard solution after pretreatment were used to perform inductively coupled plasma emission spectrometry test to obtain signal spectra, as shown in the figure. Figure 2 and Figure 3 As shown, Figure 3 The curves 0, 20, 50, 100 and 200 in the graph represent the spectral curves of the standard solutions with silver concentrations of 0 μg / L, 20 μg / L, 50 μg / L, 100 μg / L and 200 μg / L, respectively. The working curve is plotted as follows: Figure 4 As shown, the correlation coefficient R 2 The value reached 1.000, the lower limit of determination was 2.0 μg / L, and the recovery rate was 93.5-104.0%.

[0083] (7) The sample solution to be tested after pretreatment is subjected to inductively coupled plasma emission spectroscopy test to obtain spectral results, and the dissolved silver content in the sample primary loop oxidation operation water is calculated. The results are shown in Table 1.

[0084] The working conditions of the inductively coupled plasma emission spectrometer include: the carrier gas is argon, the nebulizer gas flow rate is 0.5 L / min; the cooling gas flow rate is 12 L / min; the auxiliary gas flow rate is 0.5 L / min; the measurement spectrum line is 328.068 nm; the measurement mode is horizontal; the RF generator power is 1150 W; the exposure time is 10 s; the pump speed is 50 RPM; the slit position is selected as high; the left and right backgrounds are selected as "fixed"; the injection delay is 30 s; and the cleaning is 30 s.

[0085] Example 2

[0086] This embodiment provides a method for determining the silver content in boron-containing water, and determines the dissolved silver content in the primary power operation water of a pressurized water reactor nuclear power plant. The boron content in the primary power operation water of the pressurized water reactor nuclear power plant is 1072 mg / L.

[0087] The determination method comprises the following steps:

[0088] (1) Preparation of dilution solution:

[0089] The three-level diluent includes: a primary diluent, a secondary diluent, and a tertiary diluent.

[0090] The first-level dilution solution is 1+99 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:99.

[0091] The secondary dilution solution is a boric acid solution with a boron concentration of 1000 mg / L.

[0092] The tertiary dilution solution is a 1+1 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:1.

[0093] The nitric acid used was Merck ultrapure nitric acid with a mass fraction of 65%.

[0094] The boric acid used was Merck high-purity boric acid with a purity of 99.9999%.

[0095] (2) Prepare blank standard solution, which is the secondary dilution solution.

[0096] (3) Preparation of standard solution:

[0097] A silver standard solution was selected, the silver standard solution was the silver standard solution of the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, the national standard sample number was GSB04-1712-2004, the concentration was 1000 mg / L, the relative expanded uncertainty Ur / % (k=2) was 0.7, and it was stored at room temperature away from light.

[0098] The silver standard solution was mixed with the primary diluent to dilute the silver standard solution to 1 mg / L to obtain a silver stock standard solution.

[0099] The silver stock standard solution was diluted with the secondary diluent to obtain standard solutions with silver concentrations of 20 μg / L, 50 μg / L, 100 μg / L and 200 μg / L, respectively.

[0100] (3) Prepare a sample solution to be tested. Filter the primary circuit power operating water of the pressurized water reactor nuclear power plant to be tested through a 0.45 μm filter membrane to obtain the sample solution to be tested.

[0101] (4) Test solution pretreatment:

[0102] Add the tertiary diluent to the blank standard solution, standard solution and sample solution in the same proportion, with the addition ratio of 2 mL of the tertiary diluent to every 50 mL of solution, to obtain the blank standard solution, standard solution and sample solution for testing.

[0103] (5) Perform background correction:

[0104] The left background was optimized to 328.052 nm and the right background was optimized to 328.085 nm and fixed.

[0105] (6) Draw the working curve:

[0106] After fixing the left and right backgrounds, the blank standard solution and standard solution after pretreatment were used to perform inductively coupled plasma emission spectrometry test and a working curve was drawn, such as Figure 5 As shown, the correlation coefficient R 2 The value reached 1.000, the lower limit of determination was 2.0 μg / L, and the recovery rate was 95.8-106.1%.

[0107] (7) The sample solution to be tested after pretreatment is subjected to inductively coupled plasma emission spectroscopy test to obtain spectral results, and the dissolved silver content in the sample primary circuit power operation water is calculated. The results are shown in Table 1.

[0108] The working conditions of the inductively coupled plasma emission spectrometer include: the carrier gas is argon, the nebulizer gas flow rate is 0.5 L / min; the cooling gas flow rate is 12 L / min; the auxiliary gas flow rate is 0.5 L / min; the measurement spectrum line is 328.068 nm; the measurement mode is horizontal; the RF generator power is 1150 W; the exposure time is 10 s; the pump speed is 50 RPM; the slit position is selected as high; the left and right backgrounds are selected as "fixed"; the injection delay is 30 s; and the cleaning is 30 s.

[0109] Example 3

[0110] This embodiment provides a method for determining the silver content in boron-containing water, and is directed to determining the total silver content in water used in primary oxidation operation of a pressurized water reactor nuclear power plant.

[0111] Compared with Example 1, the determination method is the same as Example 1 except that no filtering is performed in step (3).

[0112] Example 4

[0113] This embodiment provides a method for determining the silver content in boron-containing water. Compared with Example 1, the boron concentration of the secondary dilution solution is controlled to be 1500 mg / L, and the rest is the same as Example 1.

[0114] Example 5

[0115] This embodiment provides a method for determining the silver content in boron-containing water. Compared with Example 1, the primary dilution liquid is controlled to be 5+99 (V / V) nitric acid solution, and the rest is the same as Example 1.

[0116] Example 6

[0117] This embodiment provides a method for determining the silver content in boron-containing water. Compared with Embodiment 1, the background correction in step (5) is not performed, and the instrument automatically selects the left background as 328.038 nm and the right background as 328.092 nm. The rest is the same as Embodiment 1.

[0118] Comparative Example 1

[0119] This comparative example provides a method for determining the silver content in boron-containing water. Compared with Example 1, the test solution pretreatment in step (4) is not performed, and the rest is the same as Example 1.

[0120] Comparative Example 2

[0121] This comparative example provides a method for determining the silver content in boron-containing water. Compared with Example 1, an equal volume of the secondary dilution liquid is replaced with pure water, and the rest is the same as Example 1.

[0122] Comparative Example 3

[0123] This comparative example provides a method for determining the silver content in boron-containing water. Compared with Example 1, an equal volume of the primary diluent is replaced with pure water, and the rest is the same as Example 1.

[0124] The following application examples and comparative application examples use a boron-containing standard silver solution as the test solution to illustrate the technical solution of the present invention.

[0125] Application Example 1

[0126] This application example provides a method for determining the silver content in boron-containing water, using a boron-containing standard silver solution as the test solution, wherein the boron-containing standard silver solution has a dissolved silver content of 50 μg / L and a boron content of 2000 mg / L, and the determination method comprises the following steps:

[0127] (1) Preparation of dilution solution:

[0128] The three-level diluent includes: a primary diluent, a secondary diluent, and a tertiary diluent.

[0129] The first-level dilution solution is 1+99 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:99.

[0130] The secondary dilution solution is a boric acid solution with a boron concentration of 2000 mg / L.

[0131] The tertiary dilution solution is a 1+1 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:1.

[0132] The nitric acid used was Merck ultrapure nitric acid with a mass fraction of 65%.

[0133] The boric acid used was Merck high-purity boric acid with a purity of 99.9999%.

[0134] (2) Prepare blank standard solution, which is the secondary dilution solution.

[0135] (3) Preparation of standard solution:

[0136] A silver standard solution was selected, the silver standard solution was the silver standard solution of the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, the national standard sample number was GSB04-1712-2004, the concentration was 1000 mg / L, the relative expanded uncertainty Ur / % (k=2) was 0.7, and it was stored at room temperature away from light.

[0137] The silver standard solution was mixed with the primary diluent to dilute the silver standard solution to 1 mg / L to obtain a silver stock standard solution.

[0138] The silver stock standard solution was diluted with the secondary diluent to obtain standard solutions with silver concentrations of 20 μg / L, 50 μg / L, 100 μg / L and 200 μg / L, respectively.

[0139] (3) Prepare a sample solution to be tested, and take the boron-containing standard silver solution as the sample solution to be tested.

[0140] (4) Test solution pretreatment:

[0141] Add the tertiary diluent to the blank standard solution, standard solution and sample solution in the same proportion, with the addition ratio of 2 mL of the tertiary diluent to every 50 mL of solution, to obtain the blank standard solution, standard solution and sample solution for testing.

[0142] (5) Perform background correction:

[0143] The left and right backgrounds were fixed at 328.052 nm and 328.085 nm, respectively.

[0144] (6) Draw the working curve:

[0145] After fixing the left and right backgrounds, the blank standard solution and the standard solution after pretreatment were used to perform inductively coupled plasma emission spectroscopy test, and the signal spectrum was obtained to draw a working curve.

[0146] (7) The sample solution to be tested after pretreatment is subjected to inductively coupled plasma emission spectroscopy test to obtain spectral results and calculate the dissolved silver content.

[0147] The working conditions of the inductively coupled plasma emission spectrometer include: the carrier gas is argon, the nebulizer gas flow rate is 0.5 L / min; the cooling gas flow rate is 12 L / min; the auxiliary gas flow rate is 0.5 L / min; the measurement spectrum line is 328.068 nm; the measurement mode is horizontal; the RF generator power is 1150 W; the exposure time is 10 s; the pump speed is 50 RPM; the slit position is selected as high; the left and right backgrounds are selected as "fixed"; the injection delay is 30 s; and the cleaning is 30 s.

[0148] That is, the measuring method is the same as that in Example 1.

[0149] Application Example 2

[0150] This application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 1, the boron concentration of the secondary dilution liquid is controlled to be 1500 mg / L, and the rest is the same as Application Example 1.

[0151] Application Example 3

[0152] This application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 1, the first-level dilution liquid is controlled to be 5+99 (V / V) nitric acid solution, and the rest is the same as Application Example 1.

[0153] Application Example 4

[0154] This application example provides a method for determining the silver content in boron-containing water. Compared with application example 1, the background correction in step (5) is not performed, and the instrument automatically selects the left background as 328.038nm and the right background as 328.092nm. The rest is the same as application example 1.

[0155] Comparative application example 1

[0156] This comparative application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 1, the test solution pretreatment in step (4) is not performed, and the rest is the same as Application Example 1.

[0157] Comparative Application Example 2

[0158] This comparative application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 1, an equal volume of the secondary dilution liquid is replaced with pure water, and the rest is the same as Application Example 1.

[0159] Application Example 5

[0160] This application example provides a method for determining the silver content in boron-containing water, using a boron-containing standard silver solution as the test solution, wherein the boron-containing standard silver solution has a dissolved silver content of 50 μg / L and a boron content of 1000 mg / L, and the determination method comprises the following steps:

[0161] (1) Preparation of dilution solution:

[0162] The three-level diluent includes: a primary diluent, a secondary diluent, and a tertiary diluent.

[0163] The first-level dilution solution is 1+99 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:99.

[0164] The secondary dilution solution is a boric acid solution with a boron concentration of 1000 mg / L.

[0165] The tertiary dilution solution is a 1+1 (V / V) nitric acid solution, that is, the volume ratio of nitric acid to water is 1:1.

[0166] The nitric acid used was Merck ultrapure nitric acid with a mass fraction of 65%.

[0167] The boric acid used was Merck high-purity boric acid with a purity of 99.9999%.

[0168] (2) Prepare blank standard solution, which is the secondary dilution solution.

[0169] (3) Preparation of standard solution:

[0170] A silver standard solution was selected, the silver standard solution was the silver standard solution of the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, the national standard sample number was GSB04-1712-2004, the concentration was 1000 mg / L, the relative expanded uncertainty Ur / % (k=2) was 0.7, and it was stored at room temperature away from light.

[0171] The silver standard solution was mixed with the primary diluent to dilute the silver standard solution to 1 mg / L to obtain a silver stock standard solution.

[0172] The silver stock standard solution was diluted with the secondary diluent to obtain standard solutions with silver concentrations of 20 μg / L, 50 μg / L, 100 μg / L and 200 μg / L, respectively.

[0173] (3) Prepare a sample solution to be tested, and take the boron-containing standard silver solution as the sample solution to be tested.

[0174] (4) Test solution pretreatment:

[0175] Add the tertiary diluent to the blank standard solution, standard solution and sample solution in the same proportion, with the addition ratio of 2 mL of the tertiary diluent to every 50 mL of solution, to obtain the blank standard solution, standard solution and sample solution for testing.

[0176] (5) Perform background correction:

[0177] The left background was optimized to 328.052 nm and the right background was optimized to 328.085 nm and fixed.

[0178] (6) Draw the working curve:

[0179] After fixing the left and right backgrounds, the blank standard solution and standard solution after pretreatment were used to perform inductively coupled plasma emission spectrometry test and draw a working curve.

[0180] (7) The sample solution to be tested after pretreatment is subjected to inductively coupled plasma emission spectroscopy test to obtain spectral results, and the dissolved silver content is calculated.

[0181] The working conditions of the inductively coupled plasma emission spectrometer include: the carrier gas is argon, the nebulizer gas flow rate is 0.5 L / min; the cooling gas flow rate is 12 L / min; the auxiliary gas flow rate is 0.5 L / min; the measurement spectrum line is 328.068 nm; the measurement mode is horizontal; the RF generator power is 1150 W; the exposure time is 10 s; the pump speed is 50 RPM; the slit position is selected as high; the left and right backgrounds are selected as "fixed"; the injection delay is 30 s; and the cleaning is 30 s.

[0182] That is, the measuring method is the same as that in Example 2.

[0183] Application Example 6

[0184] This application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 5, the boron concentration of the secondary dilution solution is controlled to be 500 mg / L, and the rest is the same as Application Example 5.

[0185] Application Example 7

[0186] This application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 5, the first-level dilution liquid is controlled to be 5+99 (V / V) nitric acid solution, and the rest is the same as Application Example 5.

[0187] Application Example 8

[0188] This application example provides a method for determining the silver content in boron-containing water. Compared with application example 5, the background correction in step (5) is not performed, and the instrument automatically selects the left background as 328.038nm and the right background as 328.092nm. The rest is the same as application example 5.

[0189] Comparative Application Example 3

[0190] This comparative application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 5, the test solution pretreatment in step (4) is not performed, and the rest is the same as Application Example 5.

[0191] Comparative Application Example 4

[0192] This comparative application example provides a method for determining the silver content in boron-containing water. Compared with Application Example 5, an equal volume of the secondary dilution liquid is replaced with pure water, and the rest is the same as Application Example 5.

[0193] The measurement results of the embodiments and comparative examples are listed in Table 1, and the measurement results of the application examples and comparative application examples are listed in Table 2.

[0194] Table 1

[0195]

[0196]

[0197] Table 2

[0198]

[0199]

[0200] It can be seen from Table 1 and Table 2 that the method provided by the present invention can realize the determination of the silver content in boron-containing water, solves the problem of interference of boron in boron-containing water on silver determination, and the determination result is accurate. The total silver and dissolved silver contents in the sample can be determined respectively by whether or not the membrane filtration operation is performed.

[0201] Compared with Example 1, Application Example 1 and Application Example 5, in the comparative example and comparative application example, no acidification pretreatment or boric acid matrix matching of the sample is performed, which has a significant impact on the measurement results and affects the accuracy of the measurement results.

[0202] In summary, the determination method provided by the present invention can realize accurate and rapid detection of the silver content in the boron-containing water of a nuclear power plant through pretreatment of the test solution used, solve the problem of boron interference therein, improve the detection accuracy of the silver content, and provide support for the chemical control of nuclear power loop water.

[0203] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for determining the silver content in boron-containing water, characterized in that: The determination method comprises the following steps: (1) preparing a blank standard solution and a standard working solution using a primary diluent and a secondary diluent, and pretreating the blank standard solution, the standard working solution and the sample solution using a tertiary diluent; The primary diluent includes a nitric acid solution, the secondary diluent includes a boron solution, and the tertiary diluent includes a nitric acid solution; (2) The silver content of the sample solution was determined by inductively coupled plasma emission spectroscopy.

2. The measuring method according to claim 1, characterized in that In the primary dilution solution of step (1), the volume ratio of nitric acid to water is (0.5-1.5):

99.

3. The measuring method according to claim 1 or 2, characterized in that In the secondary dilution solution of step (1), the concentration of boron is 1000-2000 mg / L.

4. The assay method according to any one of claims 1 to 3, characterized in that In the tertiary dilution solution of step (1), the volume ratio of nitric acid to water is (0.8-1.2):

1.

5. The assay method according to any one of claims 1 to 4, characterized in that The method for preparing the standard working solution in step (1) comprises: mixing a silver standard solution with the primary diluent to obtain a silver reserve standard solution, and diluting the silver reserve standard solution with the secondary diluent to obtain silver standard working solutions of different concentrations; Preferably, the blank standard solution in step (1) is a secondary dilution solution.

6. The assay method according to any one of claims 1 to 5, characterized in that The dosage of the tertiary dilution solution in step (1) is (1.5-2.5) mL / 50 mL solution.

7. The assay method according to any one of claims 1 to 6, characterized in that The determination method further comprises: when determining the dissolved silver content, filtering the boron-containing water using a filter membrane below 0.45 μm to obtain a sample solution to be tested.

8. The assay method according to any one of claims 1 to 7, characterized in that In step (2), the silver content of the sample solution to be tested is determined by inductively coupled plasma emission spectrometry, using an inductively coupled plasma emission spectrometer, and the determination process includes: (a) Perform background correction of inductively coupled plasma emission spectroscopy; (b) using the pretreated blank standard solution and the standard working solution to draw a standard working curve; (c) The pretreated sample solution is measured to calculate the silver content.

9. The measuring method according to claim 8, characterized in that The background correction method in step (a) comprises: fixing the spectral signal at the positions where the boron interference is the smallest on both sides of the silver analysis line as the left background and the right background respectively; Preferably, the left background is 328.052nm, and the right background is 328.085nm; Preferably, the calculation formula of the silver content in step (c) is as follows: C=(Sa) / b Wherein, C is the silver content in the sample, S is the peak signal value of the sample after silver correction, a is the intercept of the silver standard curve, and b is the slope of the silver standard curve.

10. The measuring method according to claim 8 or 9, characterized in that The gas flow rate of the atomizer of the inductively coupled plasma emission spectrometer is 0.4-0.6 L / min; Preferably, the cooling gas flow rate of the inductively coupled plasma emission spectrometer is 10-15 L / min; Preferably, the auxiliary gas flow rate of the inductively coupled plasma optical emission spectrometer is 0.4-0.6 L / min; Preferably, the analysis line of the inductively coupled plasma emission spectrometer is 328.068 nm; Preferably, the radio frequency generator power of the inductively coupled plasma emission spectrometer is 1100-1200W; Preferably, the exposure time of the inductively coupled plasma optical emission spectrometer is 8-12s; Preferably, the pump speed of the inductively coupled plasma emission spectrometer is 45-55RPM; preferably, the injection delay of the inductively coupled plasma emission spectrometer is 25-35s.

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