CN114544858A - Method for analyzing and detecting content of uranium in uranium hexafluoride - Google Patents

Abstract

The invention belongs to the technical field of uranium mining and metallurgy analysis and measurement, in particular to a method for analyzing and detecting uranium content in uranium hexafluoride. The main steps are: after separating the uranium hexafluoride sample, add water to hydrolyze, and separate the hydrolyzate; add sulfamic acid solution to wash the wall of the cup, then directly add ferrous sulfate solution, and stir; place the beaker in a water bath, adjust the water bath The temperature of the pot is 35℃～45℃; add the oxidant solution along the inner wall of the beaker; continue to stir and let stand to make the bubbles disappear; add the vanadyl sulfate solution; pre-add a certain volume concentration of 1% potassium dichromate standard to the sample solution solution, input the sample weight and the pre-added standard potassium dichromate standard solution volume in the computer titration software interface, after titration to the stop potential, switch to the potassium dichromate standard solution with a concentration of 0.06%, according to the automatic potentiometric titrator The percentage of uranium in the sample is automatically calculated by the computer. The analysis operation of the invention is simple, safe and fast, and is suitable for the analysis of large batches of samples in enterprises.

Description

A kind of analysis and detection method of uranium content in uranium hexafluoride

technical field

The invention belongs to the technical field of uranium mining and metallurgy analysis and measurement, in particular to a method for analyzing and detecting uranium content in uranium hexafluoride.

Background technique

Natural uranium hexafluoride is an important raw material for uranium enrichment. At present, the domestic method for the determination of uranium content in uranium hexafluoride has the national standard "GB/T 14501.6.1-2008: Uranium hexafluoride analysis method" Part 6 Determination of uranium . The analysis steps of this method are as follows:

Hydrolyze the uranium hexafluoride sample, take the uranium hexafluoride hydrolyzate, reduce uranium (VI) to uranium (IV) with ferrous sulfate in a phosphoric acid medium, and use molybdenum (VI) as a catalyst at a suitable temperature, The excess iron(II) was oxidized with nitric acid, the nitrogen oxides produced during the oxidation were eliminated with sulfamic acid, and most of the uranium ( IV), and then titrated with potassium dichromate solution to the end point.

In the above-mentioned prior art, only using a potassium dichromate standard solution with a concentration of 0.8g/L for manual titration, the analysis process takes a long time, the end point control has human error, and the volume calculation of the consumed potassium dichromate solution is relatively complicated. , not suitable for large-scale sample analysis.

In view of the above-mentioned shortcomings in the prior art, it is urgent to design an improved method for analyzing and detecting uranium content in uranium hexafluoride.

SUMMARY OF THE INVENTION

The purpose of the present invention is to design a method for analyzing and detecting uranium content in uranium hexafluoride, improve the accuracy and precision, and realize the determination of uranium content in uranium hexafluoride in the analysis of large batches of samples of uranium hexafluoride production enterprises.

In order to achieve the above object, the technical scheme adopted by the present invention is:

A method for measuring uranium content in uranium hexafluoride, comprising the following steps:

(1) Clean the sample tube, dry it at 110±5℃ for 2 hours, and cool it to room temperature in a desiccator.

(2) Connect the sample tube to the sample separation device, take 8-12g of UF6 from the sample container into the sample tube, and then immerse it in liquid nitrogen to solidify the UF6. When the solidification is complete, remove the sample from the sample separation device. Remove the sample tube from the top, put on the gasket immediately, and tighten the nut and plug.

(3) Put the sample tube containing the sample in a desiccator and let it stand for more than 3 hours, so that it can reach the temperature of the surrounding environment to evaporate the condensed water. Weigh the sample tube containing the sample to the nearest 0.1 mg and record the mass.

(4) Weigh the mass of the washed and dried 500mL wide-mouth polyethylene bottle, accurate to 0.1 mg, and record the mass. The cap should ensure that the liquid is well sealed.

(5) Add 100 mL of water to the bottle and place the bottle in a beaker filled with ice and water. The amount of water added should be such that the sample tube containing the sample is submerged under the liquid surface.

(6) Tie a line on the sample tube containing the sample, and immerse the sample tube in liquid nitrogen to completely immerse the sample tube for 10 minutes.

(7) Take out the sample tube from the liquid nitrogen, untie the wire, immediately remove the plug and nut, put the gasket and the sample tube into the polyethylene bottle, keep the mouth of the sample tube immersed in water, cover the bottle cap and screw tight.

(8) Take the polyethylene bottle out of the ice water and place it in a fume hood, keep the sample tube submerged in water, and slowly hydrolyze the sample. If necessary, shake the bottle carefully to facilitate hydrolysis.

(9) When completely hydrolyzed, take out the sample tube and gasket with tweezers, wash with water, and put the cleaning solution into the bottle. Dry the outside of the bottle, tighten the cap, weigh the bottle and solution to the nearest 0.1 mg, and record the mass. Shake well.

(10) Wash the sample tube, gasket, plug and nut with water, then clean with alcohol, dry at 110±5°C for 2 hours, install the complete set, dry for 0.5 hours, and weigh the mass after cooling, accurate to 0.1 mg, Record quality.

(11) Weigh the uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium as a sample, accurate to 0.1 mg, and record the mass; transfer the sample to a 400 mL fluorine-resistant beaker, add 30 mL of concentrated phosphoric acid, and stir evenly.

(12) Under stirring, add 5 mL of sulfamic acid saturated solution. Add 8 mL of ferrous sulfate solution to the sample solution with a pipette, and do not flow down the wall of the beaker. Continue stirring and reducing at room temperature for not less than 1min.

(13) Add 5 mL of sulfuric acid, adjust the temperature of the solution to 35-40 °C, add 8 mL of oxidant along the wall with a pipette, stir for 2-3 min, and then leave it for 0.5 min. After adding the oxidant, the test solution becomes brown-black, and the color should disappear within 30s.

(14) Under stirring conditions, add 90 mL of water and 10 mL of vanadyl sulfate solution along the wall. The titration was completed within 5 minutes after adding the vanadyl sulfate solution.

(15) Click start, the automatic potentiometric titrator is pre-filled with a volume of 12.00 mL of potassium dichromate standard solution with a concentration of 1%. After stirring for 1 min, start the titration with a standard solution of potassium dichromate with a concentration of 1%, and titrate to the stop potential value. -490mV, automatically switch to 0.06% dilute potassium dichromate standard solution for titration, the computer draws the titration curve in real time, and performs data processing of the first derivative of the titration curve to obtain the titration end point potential. Click start, the instrument automatically starts titration with potassium dichromate standard solution. The titration was completed within 7 minutes.

(16) by the input weighing sample and the pre-added standard potassium dichromate standard solution volume, the volume of two standard potassium dichromate solutions consumed and the end point potential, according to the result calculation formula established by the automatic potentiometric titrator software, The computer automatically calculates the percentage of uranium in the sample.

The beneficial effects obtained by the present invention are:

The repeatability standard deviation of the present invention for the analysis of uranium hexafluoride samples is less than or equal to 0.03%, which is better than the repeatability standard deviation of the national standard method of 0.042%. There is no significant difference between the method comparison experiment and the national standard method, and the precision and accuracy are high. Compared with the national standard method, the analysis operation of the invention is simpler and faster, and the automatic operation of the instrument can be realized. A skilled analyst can perform parallel titration analysis three times in 20 minutes, which is suitable for the analysis of large batches of samples in enterprises. Using the analysis method of the present invention, the analysis efficiency is greatly improved.

Detailed ways

The main steps are: after separating the uranium hexafluoride sample, add water to hydrolyze, and separate the hydrolyzate; add sulfamic acid solution to wash the wall of the cup, then directly add ferrous sulfate solution, and stir; place the beaker in a water bath, adjust the water bath The temperature of the pot is 35℃～45℃; add the oxidant solution along the inner wall of the beaker; continue to stir and let stand to make the bubbles disappear; add the vanadyl sulfate solution; pre-add a certain volume concentration of 1% potassium dichromate standard to the sample solution solution, input the sample weight and the pre-added standard potassium dichromate standard solution volume in the computer titration software interface, after titration to the stop potential, switch to the potassium dichromate standard solution with a concentration of 0.06%, according to the automatic potentiometric titrator The percentage of uranium in the sample is automatically calculated by the computer.

Example 1

The No. 1 uranium hexafluoride sample was analyzed and 6 parallel samples were made, and the relative standard deviation RSD of the method precision was calculated.

The specific analysis steps are as follows:

(1) Clean the sample tube, dry it at 110±5℃ for 2 hours, and cool it to room temperature in a desiccator.

(2) Connect the sample tube to the sample separation device, take 8-12g of UF6 from the sample container into the sample tube, and then immerse it in liquid nitrogen to solidify the UF6. When the solidification is complete, remove the sample from the sample separation device. Remove the sample tube from the top, put on the gasket immediately, and tighten the nut and plug.

(3) Put the sample tube containing the sample in a desiccator and let it stand for more than 3 hours, so that it can reach the temperature of the surrounding environment to evaporate the condensed water. Weigh the sample tube containing the sample to the nearest 0.1 mg and record the mass.

(4) Weigh the mass of the washed and dried 500mL wide-mouth polyethylene bottle, accurate to 0.1 mg, and record the mass. The cap should ensure that the liquid is well sealed.

(5) Add 100 mL of water to the bottle and place the bottle in a beaker filled with ice and water. The amount of water added should be such that the sample tube containing the sample is submerged under the liquid surface.

(6) Tie a line on the sample tube containing the sample, and immerse the sample tube in liquid nitrogen to completely immerse the sample tube for 10 minutes.

(7) Take out the sample tube from the liquid nitrogen, untie the wire, immediately remove the plug and nut, put the gasket and the sample tube into the polyethylene bottle, keep the mouth of the sample tube immersed in water, cover the bottle cap and screw tight.

(8) Take the polyethylene bottle out of the ice water and place it in a fume hood, keep the sample tube submerged in water, and slowly hydrolyze the sample. If necessary, shake the bottle carefully to facilitate hydrolysis.

(9) When completely hydrolyzed, take out the sample tube and gasket with tweezers, wash with water, and put the cleaning solution into the bottle. Dry the outside of the bottle, tighten the cap, weigh the bottle and solution to the nearest 0.1 mg, and record the mass. Shake well.

(10) Wash the sample tube, gasket, plug and nut with water, then clean with alcohol, dry at 110±5°C for 2 hours, install the complete set, dry for 0.5 hours, and weigh the mass after cooling, accurate to 0.1 mg, Record quality.

(11) Weigh 6 parts of uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium, accurate to 0.1 mg, and record the mass; transfer the samples to a 400 mL fluorine-resistant beaker, add 30 mL of concentrated phosphoric acid, and stir evenly.

(12) Under stirring, add 5 mL of sulfamic acid saturated solution. Add 8 mL of ferrous sulfate solution to the sample solution with a pipette, and do not flow down the wall of the beaker. Continue stirring and reducing at room temperature for not less than 1min.

(13) Add 5 mL of sulfuric acid, adjust the temperature of the solution to 35-40 °C, add 8 mL of oxidant along the wall with a pipette, stir for 2-3 min, and then leave it for 0.5 min. After adding the oxidant, the test solution becomes brown-black, and the color should disappear within 30s.

(14) Under stirring conditions, add 90 mL of water and 10 mL of vanadyl sulfate solution along the wall. The titration was completed within 5 minutes after adding the vanadyl sulfate solution.

(15) Click start, the instrument pre-fills 12.00 mL of potassium dichromate standard solution with a concentration of 1%. After stirring for 1 min, start the titration with a standard solution of potassium dichromate with a concentration of 1%. When the titration reaches the stop potential value of -490mV , automatically switch to 0.06% dilute potassium dichromate standard solution for titration, the computer draws the titration curve in real time, and performs data processing on the first derivative of the titration curve to obtain the titration end point potential. Click start, the instrument automatically starts titration with potassium dichromate standard solution. The titration was completed within 7 minutes.

(16) by the input weighing sample and the pre-added standard potassium dichromate standard solution volume, the volume of two standard potassium dichromate solutions consumed and the end point potential, according to the result calculation formula established by the automatic potentiometric titrator software, The computer automatically calculates the percentage of uranium in the sample.

The parallel titration results of uranium hexafluoride samples are shown in Table 1:

Table 1 uranium hexafluoride precision test result table

The relative standard deviation of the 6 parallel results is 0.036%, which meets the requirements of sample analysis and detection.

Embodiment 2

From the same uranium hexafluoride sample, A and B each took 6 parallel samples, and performed indoor repeatable experiments according to the same operation.

The specific analysis steps are as follows:

(1) Clean the sample tube, dry it at 110±5℃ for 2 hours, and cool it to room temperature in a desiccator.

(2) Connect the sample tube to the sample separation device, take 8-12g of UF6 from the sample container into the sample tube, and then immerse it in liquid nitrogen to solidify the UF6. When the solidification is complete, remove the sample from the sample separation device. Remove the sample tube from the top, put on the gasket immediately, and tighten the nut and plug.

(3) Put the sample tube containing the sample in a desiccator and let it stand for more than 3 hours, so that it can reach the temperature of the surrounding environment to evaporate the condensed water. Weigh the sample tube containing the sample to the nearest 0.1 mg and record the mass.

(4) Weigh the mass of the washed and dried 500mL wide-mouth polyethylene bottle, accurate to 0.1 mg, and record the mass. The cap should ensure that the liquid is well sealed.

(5) Add 100 mL of water to the bottle and place the bottle in a beaker filled with ice and water. The amount of water added should be such that the sample tube containing the sample is submerged under the liquid surface.

(6) Tie a line on the sample tube containing the sample, and immerse the sample tube in liquid nitrogen to completely immerse the sample tube for 10 minutes.

(7) Take out the sample tube from the liquid nitrogen, untie the wire, immediately remove the plug and nut, put the gasket and the sample tube into the polyethylene bottle, keep the mouth of the sample tube immersed in water, cover the bottle cap and screw tight.

(8) Take the polyethylene bottle out of the ice water and place it in a fume hood, keep the sample tube submerged in water, and slowly hydrolyze the sample. If necessary, shake the bottle carefully to facilitate hydrolysis.

(9) When completely hydrolyzed, take out the sample tube and gasket with tweezers, wash with water, and put the cleaning solution into the bottle. Dry the outside of the bottle, tighten the cap, weigh the bottle and solution to the nearest 0.1 mg, and record the mass. Shake well.

(10) Wash the sample tube, gasket, plug and nut with water, then clean with alcohol, dry at 110±5°C for 2 hours, install the complete set, dry for 0.5 hours, and weigh the mass after cooling, accurate to 0.1 mg, Record quality.

(11) Two people weigh 6 parts of uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium, accurate to 0.1 mg, and record the mass; transfer the samples to a 400 mL fluorine-resistant beaker, add 30 mL of concentrated phosphoric acid, and stir evenly .

(12) Under stirring, add 5 mL of sulfamic acid saturated solution. Add 8 mL of ferrous sulfate solution to the sample solution with a pipette, and do not flow down the wall of the beaker. Continue stirring and reducing at room temperature for not less than 1min.

(13) Add 5 mL of sulfuric acid, adjust the solution temperature to 35 to 40 °C, add 8 mL of oxidant along the wall with a pipette, stir for 2 to 3 minutes, and then leave it for 0.5 minutes. After adding the oxidant, the test solution becomes brown-black, and the color should disappear within 30s.

(14) Under stirring conditions, add 90 mL of water and 10 mL of vanadyl sulfate solution along the wall. The titration was completed within 5 minutes after adding the vanadyl sulfate solution.

(15) Click start, the instrument pre-fills 12.00 mL of potassium dichromate standard solution with a concentration of 1%. After stirring for 1 min, start the titration with a standard solution of potassium dichromate with a concentration of 1%. When the titration reaches the stop potential value of -490mV , automatically switch to 0.06% dilute potassium dichromate standard solution for titration, the computer draws the titration curve in real time, and performs data processing on the first derivative of the titration curve to obtain the titration end point potential. Click start, the instrument automatically starts titration with potassium dichromate standard solution. The titration was completed within 7 minutes.

(16) by the input weighing sample and the pre-added standard potassium dichromate standard solution volume, the volume of two standard potassium dichromate solutions consumed and the end point potential, according to the result calculation formula established by the automatic potentiometric titrator software, The computer automatically calculates the percentage of uranium in the sample.

The analysis results are shown in Table 2.

Table 2 Repeated experiments

From the data in Table 2, the analysis results of A and B are consistent, and the repeatability is good, which is better than the indoor repeatability of 0.042% required by the national standard.

Embodiment 3

This method is compared with the national standard "GB/T 14501.6.1-2008: Analytical Methods of Uranium Hexafluoride Part 6: Determination of Uranium", and six parallel samples were made by the same person.

The specific analysis steps are as follows:

(1) Clean the sample tube, dry it at 110±5℃ for 2 hours, and cool it to room temperature in a desiccator.

(2) Connect the sample tube to the sample separation device, take 8-12g of UF6 from the sample container into the sample tube, and then immerse it in liquid nitrogen to solidify the UF6. When the solidification is complete, remove the sample from the sample separation device. Remove the sample tube from the top, put on the gasket immediately, and tighten the nut and plug.

(3) Put the sample tube containing the sample in a desiccator and let it stand for more than 3 hours, so that it can reach the temperature of the surrounding environment to evaporate the condensed water. Weigh the sample tube containing the sample to the nearest 0.1 mg and record the mass.

(4) Weigh the mass of the washed and dried 500mL wide-mouth polyethylene bottle, accurate to 0.1 mg, and record the mass. The cap should ensure that the liquid is well sealed.

(5) Add 100 mL of water to the bottle and place the bottle in a beaker filled with ice and water. The amount of water added should be such that the sample tube containing the sample is submerged under the liquid surface.

(6) Tie a line on the sample tube containing the sample, and immerse the sample tube in liquid nitrogen to completely immerse the sample tube for 10 minutes.

(7) Take out the sample tube from the liquid nitrogen, untie the wire, immediately remove the plug and nut, put the gasket and the sample tube into the polyethylene bottle, keep the mouth of the sample tube immersed in water, cover the bottle cap and screw tight.

(8) Take the polyethylene bottle out of the ice water and place it in a fume hood, keep the sample tube submerged in water, and slowly hydrolyze the sample. If necessary, shake the bottle carefully to facilitate hydrolysis.

(9) When completely hydrolyzed, take out the sample tube and gasket with tweezers, wash with water, and put the cleaning solution into the bottle. Dry the outside of the bottle, tighten the cap, weigh the bottle and solution to the nearest 0.1 mg, and record the mass. Shake well.

(10) Wash the sample tube, gasket, plug and nut with water, then clean with alcohol, dry at 110±5°C for 2 hours, install the complete set, dry for 0.5 hours, and weigh the mass after cooling, accurate to 0.1 mg, Record quality.

(11) Weigh 6 parts of uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium, accurate to 0.1 mg, and record the mass; transfer the samples to a 400 mL fluorine-resistant beaker, add 30 mL of concentrated phosphoric acid, and stir evenly.

(12) Under stirring, add 5 mL of sulfamic acid saturated solution. Add 8 mL of ferrous sulfate solution to the sample solution with a pipette, and do not flow down the wall of the beaker. Continue stirring and reducing at room temperature for not less than 1min.

(13) Add 5 mL of sulfuric acid, adjust the temperature of the solution to 35-40 °C, add 8 mL of oxidant along the wall with a pipette, stir for 2-3 min, and then leave it for 0.5 min. After adding the oxidant, the test solution becomes brown-black, and the color should disappear within 30s.

(14) Under stirring conditions, add 90 mL of water and 10 mL of vanadyl sulfate solution along the wall. The titration was completed within 5 minutes after adding the vanadyl sulfate solution.

(15) Click Start, the instrument pre-fills 12.00 mL of potassium dichromate standard solution with a concentration of 1%. After stirring for 1 min, start titration with a standard solution of potassium dichromate with a concentration of 1%. When the titration reaches the stop potential value of -490mV , automatically switch to 0.06% dilute potassium dichromate standard solution for titration, the computer draws the titration curve in real time, and performs data processing of the first derivative of the titration curve to obtain the titration end point potential. Click start, the instrument automatically starts titration with potassium dichromate standard solution. The titration was completed within 7 minutes.

(16) by the input weighing sample and the pre-added standard potassium dichromate standard solution volume, the volume of two standard potassium dichromate solutions consumed and the end point potential, according to the result calculation formula established by the automatic potentiometric titrator software, The computer automatically calculates the percentage of uranium in the sample.

At the same time, the same uranium hexafluoride sample was analyzed using the national standard "GB/T 14501.6.1-2008: Analytical Methods for Uranium Hexafluoride Part 6: Determination of Uranium". The data are as follows, see Table 3.

Table 3 method of the present invention and national standard method comparative analysis experiment table

The relative standard deviation of the present invention is less than or equal to 0.036%, which is better than the relative standard deviation of the national standard method of 0.055%.

Claims (9)

1. A method for analyzing and detecting the content of uranium in uranium hexafluoride is characterized by comprising the following steps: the method comprises the following steps:

(1) cleaning the sample tube, drying for 2h at the temperature of 110 +/-5 ℃, and cooling to room temperature in a dryer;

(2) connecting the sample tube with sample dividing equipment, dividing 8-12 g of uranium hexafluoride from a sample container into the sample tube, immersing the sample tube into liquid nitrogen to solidify the uranium hexafluoride, taking the sample tube from the sample dividing equipment after the uranium hexafluoride is completely solidified, immediately placing a gasket, a fastening nut and a plug;

(3) placing the sample tube with the sample in a dryer and standing for more than 3h to make the sample tube reach the temperature of the surrounding environment so as to evaporate condensed water; weighing the mass of the sample tube filled with the sample to be accurate to 0.1mg, and recording the mass;

(4) weighing the mass of a cleaned and dried 500mL wide-mouth polyethylene bottle to be accurate to 0.1mg, and recording the mass; the bottle cap should ensure good sealing of the liquid;

(5) adding 100mL of water to the bottle, and placing the bottle in a beaker containing ice and water; the amount of water added is such that the sample tube containing the sample is submerged below the liquid level;

(6) tying a line on a sample tube filled with a sample, immersing the sample tube into liquid nitrogen to completely immerse the sample tube, and keeping for 10 min;

(7) taking out the sample tube from the liquid nitrogen, releasing the line, immediately removing the plug and the nut, putting the gasket and the sample tube into a polyethylene bottle, keeping the opening of the sample tube immersed in water, covering a bottle cap and screwing;

(8) taking the polyethylene bottle out of the ice water and placing the polyethylene bottle in a ventilation cabinet, and keeping the sample tube submerged in the water all the time to slowly hydrolyze the sample;

(9) after complete hydrolysis, taking out the sample tube and the gasket by using tweezers, washing by using water, and merging the washing liquid into a bottle; wiping the outside of the bottle, screwing the bottle cap, weighing the bottle and the solution until the mass is accurate to 0.1mg, recording the mass, and shaking up;

(10) washing the sample tube, the gasket, the plug and the nut with water, then washing with alcohol, drying at 110 +/-5 ℃ for 2h, installing a set of the sample tube, the plug and the nut, drying for 0.5h, weighing the mass of the sample tube after cooling, and accurately measuring the mass to 0.1mg, and recording the mass;

(11) weighing a uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium as a sample, accurately measuring the sample to 0.1mg, and recording the mass; transferring the sample to a 400mL fluorine-resistant beaker, adding concentrated phosphoric acid, and uniformly stirring;

(12) under the condition of stirring, 5mL of sulfamic acid saturated solution is added; adding 8mL of ferrous sulfate solution into the sample solution by a pipette, wherein the ferrous sulfate solution cannot flow down along the wall of the beaker; continuously stirring at room temperature for reduction for no less than 1 min;

(13) adding 5mL of sulfuric acid, adjusting the temperature of the solution, adding 8mL of oxidant along the wall by using a pipette, stirring for 2-3 min, and then placing for 0.5 min; after the oxidant is added, the test solution becomes brownish black, and the color disappears in 30 s;

(14) adding water and vanadyl sulfate solution along the wall under the condition of stirring; completing titration within 5min after adding vanadyl sulfate solution;

(15) the automatic potentiometric titrator equipped with platinum rod electrodes was turned on and the method parameters were entered from the computer software: the reaction direction is set as negative; minimum latency 0 s; a maximum waiting time of 50 s; the liquid adding speed is 5.00 mL/min; signal drift 4; the minimum liquid adding volume is 10.00 mu L; stop volume 50.00 mL; the potential evaluation value was 35 mV; the volume after the equivalence point is 1 mL; stopping measuring the potential to-700 mV; inputting the weight of a sample, and inputting a pre-concentration potassium dichromate standard solution with the volume of 12.00mL, wherein the pre-concentration of the potassium dichromate standard solution is 1%;

(16) starting clicking, pre-adding a potassium dichromate standard solution with the concentration of 1% by the instrument by 12.00mL, stirring for 1min, then starting titration by using the potassium dichromate standard solution, automatically switching to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration when the termination potential value is-490 mV, drawing a titration curve in real time by using a computer, carrying out data processing of a first derivative on the titration curve, and automatically searching the titration end point potential by the instrument;

the formula is as follows:

wherein:

the electrode measures the electromotive force of the working cell

Δ V- -volume of addition of Standard titration solution

The click is started, and the instrument automatically starts to titrate by using a potassium dichromate standard solution; titration is completed within 7 minutes;

(17) the percentage content of uranium in the sample is automatically calculated by a computer according to a result calculation formula established by automatic potentiometric titrator software by input sample weighing, the volume of the pre-added standard potassium dichromate solution and the volume of the consumed two standard potassium dichromate solutions; the formula is as follows:

ω_{UF6 purity}-purity of uranium hexafluoride,%;

242.73- -conversion factor of potassium dichromate to uranium;

1.479- -conversion factor of uranium hexafluoride to uranium;

V₁-the volume of the concentrated potassium dichromate standard solution added, mL;

V₂-volume, mL, of diluted potassium dichromate standard solution added at the end point;

ρ₁-density of standard solution of concentrated potassium dichromate, g/mL;

ρ₂-density of diluted potassium dichromate standard solution, g/mL;

C₁-percentage concentration of concentrated potassium dichromate standard solution,%;

C₂-percent concentration of dilute potassium dichromate standard solution;

m_{test specimen}- -mass of sample, g.

2. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 1, wherein: the amount of the concentrated phosphoric acid added in the step (11) is 15 ml.

3. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 2, wherein: and (3) adjusting the temperature of the solution to 35-40 ℃.

4. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 3, wherein: 90mL of water and 10mL of vanadyl sulfate solution are added in the step (14).

5. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 4, wherein: in the step (15), the stirring speed is 8 r/min.

6. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 5, wherein: in the step (15), the mass percent concentration of the concentrated potassium dichromate standard solution is 1%, and the mass percent concentration of the dilute potassium dichromate standard solution is 0.06%.

7. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 6, wherein: and (5) pre-adding 12.00mL of 1% potassium dichromate standard solution by using an instrument in the step (15), and stirring for 1 min.

8. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 7, wherein: in the step (15), the titration is started by using a potassium dichromate standard solution with the concentration of 1%, and when the titration is carried out until the stopping potential value is-490 mV, the titration is switched to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration to an equivalent point.

9. The method for analyzing and detecting the uranium content in uranium hexafluoride of claim 8, wherein: in the step (16), titration is started by using a potassium dichromate standard solution with the concentration of 1%.