A method for detecting uranium content based on uranium molecular spectrum forming mechanism
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING RESEARCH INSTITUTE OF CHEMICAL ENGINEERING AND METALLURGY
- Filing Date
- 2022-11-28
- Publication Date
- 2026-06-09
AI Technical Summary
Existing technologies for detecting uranium content in uranium enrichments lack accuracy, and the LIBS system is significantly affected by matrix effects, resulting in low detection accuracy and failing to meet the demand for rapid and accurate detection.
A multivariate calibration model based on the formation mechanism of uranium molecular spectra is adopted. By comprehensively utilizing the characteristic spectral line intensities of uranium molecules, oxygen atoms, and uranium atoms, a method for detecting uranium content in uranium enrichments is established. The spectral signal is acquired by a laser-induced breakdown spectroscopy system and a multivariate calibration model is established to achieve rapid and accurate detection of uranium content.
It significantly improves the accuracy of uranium content detection in uranium enrichments, with a relative error of less than 2%, enabling rapid and accurate uranium content analysis.
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Figure CN116008255B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of laser-induced breakdown spectroscopy detection technology in the field of atomic emission spectroscopy measurement, and specifically relates to a method for detecting uranium content based on the uranium molecular spectrum formation mechanism. Background Technology
[0002] Uranium enrichments (mainly uranate and uranium octoxide) are my country's most important uranium hydrometallurgical products and crucial raw materials for the nuclear industry. Rapid and accurate determination of their uranium content is of paramount importance in product trading and production process control. Currently, the determination of uranium in uranium enrichments primarily employs the ferrous sulfate reduction / potassium dichromate oxidation titration method. This method uses sodium diphenylamine sulfonate as an indicator, but the operation is complex, has low automation, and is time-consuming. Furthermore, the determination of the titration endpoint is significantly influenced by human subjectivity, resulting in insufficient accuracy.
[0003] Currently, the technologies used for online uranium detection are X-ray fluorescence (XRF) and neutron-induced transient gamma-ray (NTR) analysis. However, XRF has low measurement accuracy and sensitivity, and may pose radiation risks; NTR suffers from high investment costs, radiation hazards, and short half-lives of the radioactive source. Due to these inherent limitations, these technologies have not been widely adopted. Therefore, a high-precision and rapid detection technology for uranium content in uranium enrichments is needed.
[0004] In recent years, laser-induced breakdown spectroscopy (LIBS) has emerged as a novel laser analysis technique due to its advantages such as high sensitivity, simple sample pretreatment, fast detection speed, and the ability to measure multiple elements. It holds great potential for rapid and accurate detection of uranium content in uranium enrichments. However, this technique is significantly affected by matrix effects, and current calibration models lack accuracy. Accurate quantitative measurement is the prerequisite and foundation for the rapid detection of uranium enrichments using LIBS systems, and accurate extraction of the intensity of characteristic uranium spectral signals is fundamental to the quantification of uranium. Uranium exhibits a rich emission spectrum in LIBS emission spectroscopy, and current research primarily focuses on using the characteristic emission lines of uranium atoms or the emission line information of first-order ions for quantitative analysis of uranium. However, existing research shows that uranium plasma rapidly generates uranium oxide molecules and is quenched in air or oxygen-rich environments, and this process is highly correlated with oxygen concentration. Currently, no relevant research has taken this information into account in quantitative analysis models of uranium elements, resulting in low accuracy of uranium content analysis and limiting the application of LIBS in the detection of uranium content in uranium enrichments. Therefore, it is necessary to develop a high-precision quantitative model that takes into account physical mechanisms for rapid analysis of uranium enrichments. Summary of the Invention
[0005] This invention fully utilizes the rich information in the spectral composition of uranium enrichments by LIBS detection, and provides a method for uranium content detection based on the formation mechanism of uranium molecular spectra. This method can be applied to laser-induced plasma spectroscopy systems to achieve rapid and accurate detection of uranium content in uranium enrichments.
[0006] The technical solution of the present invention is as follows:
[0007] A method for detecting uranium content based on the uranium molecular spectrum formation mechanism includes the following steps:
[0008] Step 1: Use a laser-induced breakdown spectroscopy system to acquire the spectrum of uranium enrichment standard samples and obtain the laser-induced breakdown characteristic spectrum of uranium enrichment standard samples with known uranium content;
[0009] Step 2: Extract the intensity of uranium molecular spectral peaks, oxygen atom characteristic spectral lines, and uranium atom characteristic spectral lines from the laser-induced breakdown characteristic spectrum of the uranium enrichment standard sample, and establish a multivariate calibration model of the laser-induced breakdown spectral signal intensity and the uranium content in the uranium enrichment standard sample;
[0010] Step 3: Use a laser-induced breakdown spectroscopy system to acquire the characteristic spectrum of the uranium enrichment sample to be tested. Find the characteristic peak intensities of uranium molecules, oxygen atoms, and uranium atoms that are the same as those in Step 2 from the characteristic spectrum of the uranium enrichment sample to be tested, and substitute them into the multivariate calibration model established in Step 2. The content of uranium in the uranium enrichment sample to be tested can be calculated by reverse calculation.
[0011] In step 2, the intensity I1 of the uranium molecule spectrum, which has the strongest intensity and the best correlation with uranium content, and the intensity I of all characteristic spectral lines of oxygen atoms are extracted from the characteristic spectra obtained in step 1. 2j and the intensity of all characteristic spectral lines of uranium atoms I 3k ; where I 2j I represents the intensity of the j-th characteristic spectral line of oxygen atoms in the sample. 3k The intensity of the kth characteristic spectral line representing uranium atoms in the sample;
[0012] Based on the best correlation between spectral line intensity and uranium content, from I 2j and I 3k One or two spectral lines from each sample are selected, and a multivariate calibration model is established between the laser-induced breakdown spectral signal intensity and the uranium concentration in the uranium enrichment standard sample, along with the uranium molecular peak intensity I1.
[0013] In step 2, the selected uranium molecular spectrum is the UO molecular spectrum.
[0014] In step 2, the selected uranium molecular spectrum is the UO molecular spectrum in the 595.35 nanometer band.
[0015] In step 2, the center wavelength of the extracted oxygen atom characteristic spectral line is 777.417 nm.
[0016] In step 2, the center wavelength of the extracted uranium atom characteristic spectral lines is 404.275 nm and / or 408.1 nm.
[0017] In step 1, a pulsed laser is used as the excitation source. The laser emitted from the pulsed laser is focused by a focusing lens and acts on the surface of the calibration sample. Plasma is generated at the focal point. The plasma is cooled in a protective gas atmosphere. The generated radiation light signal enters the optical fiber through the acquisition lens and is converted into an electrical signal by the spectrometer. The signal is then acquired by the computer to obtain the laser-induced breakdown characteristic spectrum of the uranium enrichment standard sample.
[0018] In step 1, the intensity of all characteristic spectral lines is obtained from the characteristic spectra of multiple uranium enrichment standard samples with known content.
[0019] The relative errors in the detection were all below 2%.
[0020] The significant advantages of this invention are:
[0021] (1) The method of the present invention can significantly improve the detection accuracy of uranium content in uranium enrichment products using laser-induced breakdown spectroscopy.
[0022] (2) Based on the formation mechanism of uranium monoxide in plasma, this invention establishes a multivariate calibration model of the signal intensity of uranium atomic spectrum, uranium molecular spectrum and oxygen atomic spectrum and the uranium content in the sample, according to the fact that the uranium content in the sample is proportional to the signal intensity of uranium atomic spectrum, uranium molecular spectrum and oxygen atomic spectrum.
[0023] (3) The method of the present invention makes comprehensive use of various information from laser-induced plasma spectroscopy and is easy to implement quickly on a computer. It can perform rapid analysis and improve measurement accuracy. Attached Figure Description
[0024] Figure 1 Schematic diagram of laser-induced breakdown spectroscopy detection of uranium enrichment;
[0025] Figure 2 This is a schematic diagram illustrating the difference between the reference value and the predicted value of uranium concentration.
[0026] In the diagram: 1. Pulsed laser; 2. Focusing lens; 3. Sample; 4. Acquisition lens; 5. Fiber optic cable; 6. Spectrometer; 7. Computer. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0028] A method for detecting uranium content based on the uranium molecular spectrum formation mechanism includes the following steps:
[0029] Step 1: Spectroscopic acquisition of uranium enrichment standard samples
[0030] The laser-induced breakdown spectroscopy system was used to acquire the spectra of uranium enrichment standard samples. A pulsed laser was used as the excitation source. The laser emitted from the pulsed laser was focused by a focusing lens and acted on the surface of the calibration sample. Plasma was generated at the focal point. The plasma was cooled in a protective gas atmosphere. The generated radiation light signal entered the optical fiber through the acquisition lens and was converted into an electrical signal by the spectrometer and acquired by the computer to obtain the laser-induced breakdown characteristic spectrum of the uranium enrichment standard sample.
[0031] The intensity of all characteristic spectral lines was obtained from the characteristic spectra of multiple uranium enrichment standard samples with known uranium contents;
[0032] Step 2: Establish a multivariate calibration model
[0033] Since the formation mechanism of UO is U + O → UO + +e and U + +O2→UO + +O, etc., it can be seen that the formation of UO is related to U, O, etc. Therefore, we consider extracting the strongest intensity uranium molecule spectral peak I1 and all characteristic spectral line intensities I of oxygen atoms from the characteristic spectrum obtained in step 1. 2j Intensities of all characteristic spectral lines of uranium atoms (I) 3k ; where I 2j I represents the intensity of the j-th characteristic spectral line of oxygen atoms in the sample. 3k The intensity of the kth characteristic spectral line representing uranium atoms in the sample is shown; the spectral intensity of uranium molecules is strongest at a wavelength of 595.35 nm, and it has the best correlation with uranium content.
[0034] Based on the best correlation between spectral line intensity and uranium content, from I 2j and I 3k One or two spectral lines from each sample are selected, and a multivariate calibration model is established between the intensity of the laser-induced breakdown spectral signal and the uranium content in the uranium enrichment standard sample, and the uranium molecular peak intensity I1 is used to establish the laser-induced breakdown spectral signal intensity and the uranium content in the uranium enrichment standard sample.
[0035] Step 3: Detect the uranium content in the uranium enrichment sample.
[0036] When testing uranium enrichment samples with unknown target content, a laser-induced breakdown spectroscopy system is used to collect the characteristic spectrum of the uranium enrichment sample to be tested, thereby obtaining the intensity of all spectral lines in the uranium enrichment sample to be tested.
[0037] Identify the characteristic peak intensities of uranium molecules, oxygen atoms, and uranium atoms from the characteristic spectrum of the uranium enrichment sample to be tested, which are identical to those in step 2. Substitute these intensities into the multivariate calibration model established in step 2. By using the correspondence between the characteristic peak intensities and the uranium content, the uranium content in the uranium enrichment sample to be tested can be calculated by back-calculating based on the characteristic spectral line intensities of the unknown sample.
[0038] Example: Uranium content measurement of a group of ammonium diuranate samples
[0039] In this example, a total of 10 standard samples were used. The uranium content in the samples was determined by traditional chemical methods (titration), and the specific information is shown in Table 1 below.
[0040] Table 1. Uranium content in ammonium diuranate standard samples
[0041]
[0042] Step 1: Spectroscopic acquisition of uranium enrichment standard samples
[0043] like Figure 1 As shown, the above ammonium diuranate standard sample was spectrally acquired using a laser-induced breakdown spectroscopy system: a pulsed laser (1) was used as the excitation source. The laser emitted from the pulsed laser (1) was focused by a focusing lens (2) and acted on the surface of the calibration sample (3). Plasma was generated at the focal point. The plasma was cooled in a protective gas atmosphere. The generated radiation light signal entered the optical fiber (5) through the acquisition lens (4) and was converted into an electrical signal after being processed by a spectrometer (6) and acquired by a computer (7) to obtain the laser-induced plasma characteristic spectrum of the standard sample.
[0044] Repeat the above spectral acquisition steps for 10 ammonium diuranate standard samples to obtain the intensity of all characteristic spectral lines from the characteristic spectrum of each sample;
[0045] Step 2: Establish a multivariate calibration model
[0046] Characteristic spectral lines related to oxygen and uranium atoms in the laser-induced breakdown spectrum were selected, and a multivariate calibration model of content and signal intensity was established. In this example, the entire calculation process was carried out using the Matlab program. The spectral lines with the best intensity and the best correlation coefficient with uranium content were finally selected as the UO molecular spectrum at 595.35 nm, the oxygen atom spectrum at a center wavelength of 777.417 nm, and the uranium atom spectra at a center wavelength of 404.275 nm and 408.1 nm.
[0047] Step 3: Verify the accuracy of the calibration model
[0048] The analysis results of the multivariate calibration model obtained using one-out-of-one cross-validation are as follows: Figure 2As shown in Table 2, the average relative prediction error is 0.78%.
[0049] The aforementioned missing cross-validation means that in the multivariate calibration model established in step 2, a certain standard sample is assumed to be an unknown sample. Then, the model prediction value of the uranium content in the standard sample is calculated through the other nine known standard sample points. The model prediction value is then compared with the actual known reference value of the standard sample to verify the difference between the two values and calculate the error between them.
[0050] Table 2. Relative errors between reference values and model predictions of uranium content in ten ammonium diuranate samples.
[0051]
[0052] The experimental results obtained in this example demonstrate that the method for detecting uranium content in uranium enrichments based on the uranium molecular spectrum formation mechanism of this invention can achieve good detection accuracy, with relative errors of less than 2% and average errors of 0.78%.
[0053] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.
[0054] Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A method for detecting uranium content based on the uranium molecular spectrum formation mechanism, characterized in that: Includes the following steps: Step 1: Use a laser-induced breakdown spectroscopy system to acquire the spectrum of uranium enrichment standard samples and obtain the laser-induced breakdown characteristic spectrum of uranium enrichment standard samples with known uranium content; Step 2: Extract the intensity of uranium molecular spectral peaks, oxygen atom characteristic spectral lines, and uranium atom characteristic spectral lines from the laser-induced breakdown characteristic spectrum of the uranium enrichment standard sample, and establish a multivariate calibration model of the laser-induced breakdown spectral signal intensity and the uranium content in the uranium enrichment standard sample; Step 3: Use a laser-induced breakdown spectroscopy system to collect the characteristic spectrum of the uranium enrichment sample to be tested. Find the characteristic peak intensities of uranium molecules, oxygen atoms, and uranium atoms that are the same as those in Step 2 from the characteristic spectrum of the uranium enrichment sample to be tested. Substitute them into the multivariate calibration model established in Step 2, and the uranium content in the uranium enrichment sample to be tested can be calculated by reverse calculation. In step 2, the intensity of the uranium molecule spectrum peak with the strongest intensity and the best correlation with uranium content is extracted from the characteristic spectrum obtained in step 1. Intensities of all characteristic spectral lines of oxygen atoms and the intensity of all characteristic spectral lines of uranium atoms ;in The first oxygen atom in the sample j The intensity of the characteristic spectral lines, The first uranium atom representing the sample k The intensity of each characteristic spectral line; Based on the fact that spectral line intensity has the best correlation with uranium content, from and Take one or two spectral lines from each spectrum and compare them with the peak intensity of the uranium molecule spectrum. A multivariate calibration model was established to correlate the intensity of the laser-induced breakdown spectral signal with the uranium concentration in the uranium enrichment standard sample.
2. The uranium content detection method based on the uranium molecular spectrum formation mechanism as described in claim 1, characterized in that: In step 2, the selected uranium molecular spectrum is the UO molecular spectrum.
3. The uranium content detection method based on the uranium molecular spectrum formation mechanism as described in claim 2, characterized in that: In step 2, the selected uranium molecular spectrum is the UO molecular spectrum in the 595.35 nanometer band.
4. The uranium content detection method based on the uranium molecular spectrum formation mechanism as described in claim 1, characterized in that: In step 2, the center wavelength of the extracted oxygen atom characteristic spectral line is 777.417 nm.
5. The uranium content detection method based on the uranium molecular spectrum formation mechanism as described in claim 1, characterized in that: In step 2, the center wavelength of the extracted uranium atom characteristic spectral lines is 404.275 nm and / or 408.1 nm.
6. The uranium content detection method based on the uranium molecular spectrum formation mechanism as described in claim 1, characterized in that: In step 1, a pulsed laser is used as the excitation source. The laser emitted from the pulsed laser is focused by a focusing lens and acts on the surface of the calibration sample. Plasma is generated at the focal point. The plasma is cooled in a protective gas atmosphere. The generated radiation light signal enters the optical fiber through the acquisition lens and is converted into an electrical signal by the spectrometer. The signal is then acquired by the computer to obtain the laser-induced breakdown characteristic spectrum of the uranium enrichment standard sample.
7. The uranium content detection method based on the uranium molecular spectrum formation mechanism as described in claim 6, characterized in that: In step 1, the intensity of all characteristic spectral lines is obtained from the characteristic spectra of multiple uranium enrichment standard samples with known content.
8. A method for detecting uranium content based on the uranium molecular spectrum formation mechanism as described in any one of claims 1 to 7, characterized in that: The relative errors in the detection were all below 2%.