A method for analyzing silicon in secondary circuit water of nuclear power plants using GFAAS

Abstract

The present invention belongs to the technical field of water chemical analysis in nuclear power plants, and specifically relates to an analysis method for analyzing silicon in the secondary loop water of a nuclear power plant using GFAAS. A silicon standard solution is prepared, and an atomic absorption spectrometer automatically dilutes the silicon standard solution into a series of concentration standard solutions, and a palladium nitrate matrix improver is prepared using palladium nitrate powder; after the atomic absorption spectrometer parameters are set, the palladium nitrate matrix improver and the series of concentration standard solutions are automatically inhaled in sequence, and injected into the graphite tube of the pyrolysis coating platform of the atomic absorption spectrometer, and the atomic absorption spectrometer is started. After the analysis is completed, the absorbance is automatically recorded, and a working standard curve is drawn; the sample is placed in the automatic sampler of the atomic absorption spectrometer, and the atomic absorption spectrometer is started, and the analysis is performed in sequence. After the analysis is completed, the absorbance is automatically recorded and the sample concentration under the corresponding absorbance is queried on the working standard curve. The operation steps of the present invention are simple and time-saving, which greatly improves the analysis efficiency and reduces the operational risk.

Description

Technical Field

[0001] The invention belongs to the technical field of water chemical analysis in nuclear power plants, and in particular relates to an analysis method for analyzing silicon in secondary loop water in nuclear power plants by utilizing GFAAS. Background Art

[0002] Graphite furnace atomic absorption spectrometry (GFAAS) is a method in which the characteristic spectrum of the element to be measured radiated by the light source passes through the ground state atoms of the element to be measured in the sample vapor. The emission spectrum is absorbed by the ground state atoms, and the content of the element to be measured in the sample is obtained from the degree of attenuation of the emission spectrum.

[0003] The secondary loop water of nuclear power plants mainly consists of chemically desalted water, steam generator feed water, steam, condensate, etc. The silicon content is relatively low, generally 0-200μg / L. The current analysis method of silicon in nuclear power plants mainly refers to "GB / T12149-2017 Determination of Silicon in Industrial Circulating Cooling Water and Boiler Water". This method requires the use of 9 chemical reagents including hazardous chemicals such as hydrochloric acid and sodium hydroxide. The analysis steps are complicated (different reagents need to be added three times) and time-consuming (5 samples take 60 minutes, including 40 minutes for sample preparation and 20 minutes for sample analysis). Summary of the invention

[0004] The present invention aims at the problems encountered and existing in the process of analyzing silicon in the secondary loop water of a nuclear power plant, and provides an analysis method for analyzing silicon in the secondary loop water of a nuclear power plant using GFAAS. Compared with the existing method, the method only uses two chemical reagents, has simple operation steps and is less time-consuming, greatly improves the analysis efficiency and reduces the operational risk.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for analyzing silicon in secondary loop water of a nuclear power plant by using GFAAS comprises the following steps: preparing a silicon standard solution, using an atomic absorption spectrometer to automatically dilute the silicon standard solution into a series of concentration standard solutions, and using palladium nitrate powder to prepare a palladium nitrate matrix improver; after the parameters of the atomic absorption spectrometer are set, the palladium nitrate matrix improver and the series of concentration standard solutions are automatically sucked in sequence, injected into a graphite tube of a pyrolytic coating platform of the atomic absorption spectrometer, the atomic absorption spectrometer is started, and after the analysis is completed, the absorbance is automatically recorded, and a working standard curve is drawn; a sample is placed in an automatic sampler of the atomic absorption spectrometer, the atomic absorption spectrometer is started, and the analysis is performed in sequence, and after the analysis is completed, the absorbance is automatically recorded and the sample concentration under the corresponding absorbance is queried on the working standard curve.

[0007] The atomic absorption spectrometer used was PE AA800 model, equipped with AS-800 autosampler, silicon hollow cathode lamp, and pyrolytic coating platform graphite tube.

[0008] The atomic absorption spectrometer was set as follows: wavelength 251.61 nm, slit 0.7 L nm, lamp current 40 mA.

[0009] The atomic absorption spectrometer was set as follows: injection volume 20 μL, injection mode automatic injection.

[0010] After the atomic absorption spectrometer parameters are set, 5 μL of palladium nitrate matrix modifier and a series of concentration standard solutions are automatically aspirated in sequence.

[0011] A palladium nitrate matrix improver with a concentration of 200 mg / L was prepared using palladium nitrate powder with a mass fraction of 40% palladium.

[0012] Use certified silicon standard solution to prepare silicon standard working solution, the concentration of silicon standard working solution is preferably 200μg / L.

[0013] The heating program of the graphite furnace in the atomic absorption spectrometer is as follows: the first drying temperature is 110°C, and the dwell time is 30s; the second drying temperature is 140°C, and the dwell time is 30s; the ashing temperature is 1000°C, and the dwell time is 20s; the atomization temperature is 2350°C, and the dwell time is 4s; the high temperature cleaning temperature is 2450°C, and the dwell time is 5s.

[0014] The concentration standard solution series contains 5-9 concentration points.

[0015] The best concentration of the series of standard solutions is 5 concentration points, namely: 0μg / L, 50μg / L, 100μg / L, 150μg / L, and 200μg / L.

[0016] The beneficial effects achieved by the present invention are:

[0017] From the characteristics of atomic absorption spectrometer, to analyze samples using this method, you only need to put the sample into the automatic sample injector of the atomic absorption spectrometer, and the instrument will automatically analyze and display the data. No other operations are required, and only two chemical reagents are used. Under the premise of ensuring the accuracy of the analysis data, the risk is greatly reduced and the analysis efficiency is significantly improved.

[0018] After actual verification, the correlation coefficient of the 0-200μg / L silicon working standard curve is 0.9999, the detection limit is 2.11μg / L, the precision is ≤1.91%, the spiked recovery rate is 91.5%-101%, and the deviation from the traditional spectrophotometric measurement results is within the range of ±10%. DETAILED DESCRIPTION

[0019] The present invention is described in detail below with reference to specific embodiments.

[0020] Through a large number of experiments, the concentration of palladium nitrate matrix modifier and the two most critical parameters in the instrument's graphite furnace heating program, the ashing temperature and the atomization temperature, were determined. The specific experimental method and instrument settings are as follows.

[0021] a. Instrument Condition Settings

[0022] Atomic absorption spectrometer It is recommended to use PE AA800 atomic absorption spectrometer equipped with AS-800 automatic sample injector, silicon hollow cathode lamp, pyrolytic coating platform graphite tube, or use an atomic absorption spectrometer with equivalent configuration.

[0023] The atomic absorption spectrometer was set as follows: wavelength 251.61 nm, slit 0.7 L nm, lamp current 40 mA, injection volume 20 μL, and injection mode automatic injection.

[0024] The heating program of the graphite furnace in the atomic absorption spectrometer is as follows: the first drying temperature is 110°C, and the dwell time is 30s; the second drying temperature is 140°C, and the dwell time is 30s; the ashing temperature is 1000°C, and the dwell time is 20s; the atomization temperature is 2350°C, and the dwell time is 4s; the high temperature cleaning temperature is 2450°C, and the dwell time is 5s.

[0025] b. Preparation of standard working solution

[0026] Use certified silicon standard solution to prepare silicon standard working solution, the concentration of silicon standard working solution is preferably 200μg / L.

[0027] The atomic absorption spectrometer automatically dilutes the silicon standard solution (200μg / L) into a series of concentration standard solutions, such as: 0μg / L, 50μg / L, 100μg / L, 150μg / L, 200μg / L. The series of concentration standard solutions can contain 5-9 concentration points, with 5 concentration points being the best.

[0028] c. Preparation of matrix modifier

[0029] A palladium nitrate matrix improver with a concentration of 200 mg / L was prepared using palladium nitrate powder with a mass fraction of 40% palladium.

[0030] d. Standard curve drawing

[0031] After the atomic absorption spectrometer parameters are set, 5 μL of palladium nitrate matrix modifier and a series of concentration standard solutions are automatically aspirated in sequence and injected into the graphite tube of the pyrolytic coating platform. The atomic absorption spectrometer is started. After the instrument completes the analysis, the absorbance is automatically recorded and a working standard curve is drawn.

[0032] e. Sample analysis

[0033] Place the sample into the atomic absorption spectrometer autosampler (multiple samples can be placed at the same time), start the atomic absorption spectrometer, and the instrument will analyze in sequence. After the instrument analysis is completed, the absorbance will be automatically recorded and the sample concentration at the corresponding absorbance will be queried on the working standard curve.

Claims

1. A method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS, characterized in that: Prepare silicon standard working solution, atomic absorption spectrometer automatically dilutes silicon standard working solution into series concentration standard solution, palladium nitrate powder is used to prepare palladium nitrate matrix modifier; after setting the parameters of atomic absorption spectrometer, palladium nitrate matrix modifier and series concentration standard solution are automatically sucked in turn, injected into the graphite tube of pyrolysis coating platform of atomic absorption spectrometer, start atomic absorption spectrometer, automatically record absorbance after analysis is completed, and draw working standard curve; put the sample into the automatic sample injector of atomic absorption spectrometer, start atomic absorption spectrometer, analyze in turn, automatically record absorbance after analysis is completed and query the sample concentration under corresponding absorbance on working standard curve; atomic absorption spectrometer uses PE Model AA800, equipped with AS-800 autosampler, silicon hollow cathode lamp, pyrolysis coating platform graphite tube; atomic absorption spectrometer settings are: wavelength 251.61nm, slit 0.7Lnm, lamp current 40mA; the graphite furnace heating program in the atomic absorption spectrometer is: first drying temperature 110℃, stay 30s; second drying temperature 140℃, stay 30s; ashing temperature 1000℃, stay 20s, atomization temperature 2350℃, stay 4s; high temperature cleaning temperature 2450℃, stay 5s.

2. The method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS according to claim 1, characterized in that: The atomic absorption spectrometer was set as follows: injection volume 20 μL, injection mode automatic injection.

3. The method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS according to claim 1, characterized in that: After the atomic absorption spectrometer parameters are set, 5 μL of palladium nitrate matrix modifier and a series of concentration standard solutions are automatically aspirated in sequence.

4. The method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS according to claim 1, characterized in that: A palladium nitrate matrix improver with a concentration of 200 mg / L was prepared using palladium nitrate powder with a mass fraction of 40% palladium.

5. The method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS according to claim 1, characterized in that: Use certified silicon standard solution to prepare silicon standard working solution, the concentration of silicon standard working solution is 200μg / L.

6. The method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS according to claim 1, characterized in that: The concentration standard solution series contains 5-9 concentration points.

7. The method for analyzing silicon in secondary circuit water of a nuclear power plant using GFAAS according to claim 6, characterized in that: The best concentration of the series of standard solutions is 5 concentration points, namely: 0μg / L, 50μg / L, 100μg / L, 150μg / L, and 200μg / L.