Method for determining krypton isotope based on electron cyclotron resonance mass spectrometer

Abstract

The invention belongs to the technical field of isotope analysis, and relates to a method for determining krypton isotope based on an electron cyclotron resonance mass spectrometer, which comprises seven steps of background noise determination, sensitivity determination, gas sample introduction detection limit determination, oxide yield and double charge yield determination, isotope precision ratio determination, stability determination and precision determination. The method can realize ionization and simultaneous measurement of krypton isotope composition under low sample content, has the advantages of low detection limit, high sensitivity, high accuracy, rapid detection and the like, provides more visual and highly reliable data for nuclear industry field check, and provides reliable data support for determination of nuclear activity properties.

Description

Technical Field

[0001] This invention belongs to the field of isotope analysis technology and relates to a method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry. Background Technology

[0002] In spent fuel from power reactors 237 Np is a transuranic element with relatively high yields besides Pu, and it has wide applications in aerospace and medical industries. Extracting neptunium through nuclear fuel cycle processes is an important method for preparing neptunium samples. Accurate measurement of the Th, U, Am, and Pu contents in neptunium dioxide is of significant reference and guiding importance for the operation and parameter optimization of the neptunium extraction process, improving the yield of neptunium dioxide powder, and ensuring sample purity.

[0003] Currently, common methods for separating actinides both domestically and internationally include solvent extraction, ion exchange, and extraction chromatography. The main drawback of solvent extraction is the generation of large amounts of organic waste liquid during the separation process, which is difficult to treat; furthermore, the extraction process is susceptible to entrainment and container wall contamination, and the separation efficiency is greatly affected by the operator's skill level. Ion exchange is widely applicable, simple to operate, and low-cost, making it suitable for micro-separation; however, its selectivity is lower than that of solvent extraction, often requiring the use of chromatographic coupling techniques or other separation techniques in combination. Extraction chromatography combines the high selectivity of solvent extraction with the high separation efficiency of ion exchange. The resin is regenerable, the operation is simple, and it is easily automated. It can be applied to the separation and purification of actinides, and the use of multi-stage resin columns can achieve stepwise separation of multiple actinides. Summary of the Invention

[0004] The present invention aims to design a pretreatment process for the stepwise separation of Th, U, Am and Pu in neptunium dioxide powder, and to achieve the stepwise separation of trace amounts of Th, U, Am and Pu in neptunium dioxide powder by using extraction chromatography resin coupled with other technologies.

[0005] The technical solution to achieve the purpose of this application is as follows:

[0006] This application provides a method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry, including the following steps:

[0007] Step 1, Background noise measurement:

[0008] An electron cyclotron resonance mass spectrometer (ECR-QMS) using an ECR ion source and a quadrupole mass analyzer was employed. Under normal instrument operation, an inert gas was introduced as the carrier gas. Under the set gas flow rate and vacuum conditions, a measurement sequence was established, a specific mass number was selected for signal acquisition, and the background noise value of the instrument was determined based on the average value of multiple scan counts.

[0009] Step 2, Sensitivity Measurement:

[0010] Under the same carrier gas conditions, krypton gas of the concentration to be measured is introduced, the mass spectrometer is tuned and the response value of a specific krypton isotope is measured. The average value of multiple sets of data is obtained and the background noise value is subtracted to obtain the sensitivity of krypton at that concentration.

[0011] Step 3, determination of gas injection detection limit:

[0012] The response values ​​of various krypton gas samples with different concentrations were measured, and the measurement standard deviation and detection limit were calculated.

[0013] The formula for calculating standard deviation is:

[0014]

[0015] Where s is the standard deviation; x i This is a single measurement value; The average value is denoted by n; n represents the number of measurements.

[0016] The formula for calculating the detection limit is:

[0017] DL = 3s / S

[0018] Where DL is the element detection limit; S is the sensitivity measured in step two;

[0019] Step 4, Determination of oxide yield and double charge yield:

[0020] Under mixed injection conditions of krypton and oxygen, the count ratios of multiple isotope ions were determined to determine the oxide yield and double charge yield.

[0021] Step 5, Isotope precision ratio determination:

[0022] By scanning and measuring different krypton isotope ions, their isotope ratios and relative standard deviations (RSD) were obtained.

[0023] The formula for calculating RSD is:

[0024] RSD = (s / X) × 100%

[0025] In the formula, s is the standard deviation; X is the arithmetic mean of the measured values;

[0026] Step 6, Stability Test:

[0027] Krypton gas was used for injection, and the gas flow rate was kept stable. A set of data was collected at intervals, and the data were recorded for 20 minutes and 2 hours respectively. The RSD of several sets of data during this period was calculated to correspond to the short-term stability and long-term stability of this type of data.

[0028] Step 7, Precision determination:

[0029] Precision represents the degree of fluctuation in data within a group during a single test, reflecting the instantaneous stability and measurement accuracy of the entire system. Measurement precision is evaluated by calculating the RSD of the ion response value after multiple repeated measurements under fixed concentration conditions.

[0030] Optionally, in step one, the inert gas used is argon, the gas flow rate is set to 0.5 sccm, and the vacuum degree is maintained at 1×10⁻⁶. -5 mbar to 6×10 -5 Between mbar.

[0031] Optionally, in step one, the instrument parameters selected are: mass number 5, dwell time 20ms, number of channels 3, interval 0.01, and number of scans 20.

[0032] Optionally, in step two, the instrument parameters are set with a gas flow rate of 0.5 sccm and a vacuum degree of approximately 5 × 10⁻⁶. -5 mbar, dwell time 20ms, number of channels 3, interval 0.02.

[0033] Optionally, in step three, the krypton gas concentration is 0 ppm, 1 ppm and 10 ppm respectively, and 10 sets of data are scanned at each concentration, with each set being scanned three times.

[0034] Optionally, in step four, the isotope ions measured include 80 Kr + , 84 Kr + as well as 42 Kr ++ , 96 KrO + and calculate 42 Kr ++ / 84 Kr + , 96 KrO + / 80 Kr + The magnitude of the double charge yield and oxide yield were obtained.

[0035] Optionally, in step five, the selected isotope is... 82 Kr and 83 Kr, instrument parameters selected: number of channels 3, dwell time 50ms, number of scans 100.

[0036] Optionally, in step seven, a krypton gas with a concentration of 1 ppm is injected at a flow rate of 0.5 sccm, and the number of scans is 10. If the RSD of all 10 scans is less than 2%, the precision is considered to be qualified.

[0037] The beneficial technical effects of this application are as follows:

[0038] Compared with traditional magnetic mass spectrometry, ECR-QMS offers higher sensitivity and lower manufacturing cost for determining Kr isotope abundance, and allows for self-maintenance, thus enabling the instrument to be domestically produced. It can simultaneously measure the isotopic composition of krypton at low concentrations and has advantages such as low detection limit, high sensitivity, high accuracy, and rapid detection. This provides more intuitive and reliable data for on-site verification in the nuclear industry and provides reliable data support for determining the nature of nuclear activities. Detailed Implementation

[0039] This invention provides a method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry. The invention is further described in detail below with reference to specific embodiments, but it should not be construed as limiting the scope of the above subject matter of the invention to the following embodiments.

[0040] This invention provides a method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry, the specific steps of which are as follows:

[0041] Step 1, Background noise measurement:

[0042] An electron cyclotron resonance mass spectrometer (ECR-QMS) using an ECR ion source coupled with a quadrupole mass analyzer was employed. Under normal operating conditions, pure Ar gas was introduced, with the gas flow rate controlled at 0.5 sccm and the vacuum maintained at 1*10⁻⁶. -5 mbar ~ 6*10 - 5 mbar. After the instrument stabilizes, establish the sequence. On the instrument operation panel, select mass number of 5 as the monitoring index of Ar, residence time of 20ms, number of channels of 3, interval of 0.01, set the number of scans to 20, record the count value and calculate its average value, which is the background noise value of the instrument.

[0043] Background noise was measured at mass numbers of 5 amu and 220 amu using pure Ar gas. The test data are as follows:

[0044] 5amu 220amu 1 1.67 0 2 0 0 3 0 0 4 0 0 5 0 1.67 6 1.67 1.67 7 0 0 8 0 0 9 0 0 10 0 0 11 0 0 12 0 0 13 1.67 0 14 0 0 15 0 0 16 0 1.67 17 0 0 18 1.67 1.67 19 0 0 20 0 0 average value 0.33 0.33 SD 0.684 0.684 RSD (%) 205.2 205.2

[0045] Step 2, Sensitivity Measurement:

[0046] Under normal operating conditions, using Ar gas as the carrier gas, Kr gas with a concentration of 1 ppm is introduced, the gas flow rate is set to 0.5 sccm, and the vacuum degree is 5*10 -5 Around mbar, select in the manual tuning scan interface of the instrument's operation panel. 84For Kr isotopes, click the scan button on the manual tuning interface and wait for the mass number response value trend graph to rise and stabilize. Create a new method, select Kr isotope, residence time 20ms, number of channels 3, interval 0.02, measure ion count, measure 10 sets of data, calculate the average value, and after subtracting the background noise value, obtain the sensitivity of Kr at this concentration.

[0047] Ten sets of data were collected using Kr isotope gases ranging from 0 to 1 to 10 ppm. The average response of each isotope gas was calculated, as shown in the table below:

[0048] ppm <![CDATA[ 83 Kr]]> <![CDATA[ 84 Kr]]> <![CDATA[ 86 Kr]]> 0 361.124 1639.604 400.683 1 25067.31 110967.8 28056.22 10 232483.6 1043509 256828.7

[0049] Step 3, determination of gas injection detection limit:

[0050] Prepare Kr gas at concentrations of 0 ppm, 1 ppm, and 10 ppm, establish three sample sequences, scan 10 sets of data in each sample sequence, and scan each set three times to obtain the response values ​​of Kr at 0 ppm, 1 ppm, and 10 ppm. At the same time, calculate the standard deviation of each count value and the limit of detection of the element at the three concentrations.

[0051] The formula for calculating standard deviation is:

[0052]

[0053] Where s is the standard deviation; x i This is a single measurement value; The average value is denoted by n; n represents the number of measurements.

[0054] The formula for calculating the detection limit is:

[0055] DL = 3s / S

[0056] Where DL is the element detection limit; S is the sensitivity measured in step two;

[0057]

[0058]

[0059] Step 4, Determination of oxide yield and double charge yield:

[0060] The dual rates mainly include oxide yield and dual charge yield. Similar to the sensitivity testing method, the test is performed under the premise of Kr+O2 mixed injection. 80 Kr + , 84 Kr + as well as 42 Kr ++ , 96 KrO +The ion count values ​​at each location were calculated separately. 42 Kr ++ / 84 Kr + , 96 KrO + / 80 Kr + The magnitude of the double charge yield and oxide yield were obtained;

[0061] The double-charge yield and oxide yield were tested using a mixed Kr gas injection method as follows:

[0062] Double charge test results:

[0063] frequency <![CDATA[ 42 Kr ++ (cps)]]> <![CDATA[ 84 Kr(cps)]]> <![CDATA[ 42 Kr ++ / 84 Kr + ]]> 1 12531 2061900 0.608％ 2 11591 2019800 0.574％ 3 10765 1974700 0.545％ 4 10811 1980700 0.546％ 5 10897 2040500 0.534％ 6 10751 2038800 0.527％ 7 9606 1883500 0.510％ 8 9484 1869700 0.507％ 9 9416 1882900 0.500％ 10 9350.7 1882300 0.497％ average value / / 0.53％

[0064] Oxide yield:

[0065] frequency <![CDATA[ 96 For]]> <![CDATA[ 80 Kr]]> <![CDATA[ 96 Inn / 80 Kr(%)]]> <![CDATA[ 100 Ru]]> <![CDATA[ 86 Kr]]> <![CDATA[ 100 Inn / 86 Kr(%)]]> 1 2 136540 0.00146％ 0.6667 916870 0.0000727％ 2 0.6667 128350 0.00052％ 1.3333 868950 0.0001534％ 3 0.6667 122120 0.00055％ 1.3333 827460 0.0001611％ 4 2.6667 122370 0.00218％ 0 815680 0.0000000％ 5 2 123740 0.00162％ 2.6667 837410 0.0003184％ 6 0.6667 123410 0.00054％ 0.6667 821770 0.0000811％ 7 0.6667 103700 0.00064％ 1.3333 524530 0.0002542％ 8 1.3333 101730 0.00131％ 0 513280 0.0000000％ 9 1.3333 102170 0.00130％ 0 523090 0.0000000％ 10 0.6667 102370 0.00065％ 0.6667 528010 0.0001263％

[0066] It can be seen that the yields of both double-charged and oxide products are less than 3%, which meets the requirements.

[0067] Step 5, Isotope precision ratio determination:

[0068] Introduce a certain concentration of Kr gas, and select the appropriate option in the ECR-QMS operating system. 82 Kr、 83 Kr, change the number of channels to 3, dwell time to 50ms, and scan count to 100. Simultaneously, click on isotope ratio and add... 82 Kr / 83 Kr. Inject Kr gas, run isotope ratios individually, and click stop after the scan is complete. View and record the Kr isotope ratios and RSD values;

[0069] RSD = (s / X) × 100%

[0070] In the formula, s is the standard deviation; X is the arithmetic mean of the measured values;

[0071] Ten sets of data were collected using Kr gas injection, and calculations were performed simultaneously. 82 Kr / 83 The ratio of Kr is used to calculate RSD, and the data is as follows:

[0072] Serial Number <![CDATA[ 82 Kr's average value for each group]]> <![CDATA[ 83 Kr's average value for each group]]> <![CDATA[ 82 Kr / 83 Kr]]> 1 3168098 3130264 1.012086 2 3092677 3052969 1.013006 3 2981331 2945414 1.012194 4 3184961 3137565 1.015106 5 3200649 3152056 1.015416 6 3083842 3035334 1.015981 7 3089435 3057473 1.010454 8 3085842 3048435 1.012271 9 2971873 2942204 1.010084 10 3113777 3078244 1.011543 average / / 1.012814 SD / / 0.002053 RSD% / / 0.203％

[0073] The isotopic precision ratio meets the requirement of RSD% ≤ 0.3%.

[0074] Step 6, Stability Test:

[0075] Stability is divided into short-term stability and long-term stability. Kr gas is injected and the gas flow rate is kept stable. A set of data is collected at regular intervals, and the data is recorded for 20 minutes and 2 hours respectively. The RSD of several sets of data during this period is calculated to correspond to the short-term stability and long-term stability of this type of data.

[0076] Short-term stability:

[0077] Analytical data were obtained by establishing a sample sequence. Ten sets of data were collected within a 20-minute timeframe, and the RSD% was calculated. The acceptable RSD% threshold was ≤3%.

[0078] Column 1 <![CDATA[ 78 Kr's average for each group]]> <![CDATA[ 80 Kr's average for each group]]> <![CDATA[ 82 Kr's average value for each group]]> <![CDATA[ 83 Kr's average for each group]]> <![CDATA[ 84 Kr's average for each group]]> <![CDATA[ 86 Kr's average for each group]]> 1 229159 1279356 3168097.82 3130264.21 16655619.4 4148496.2 2 222334.67 1253529.33 3092677.06 3052969.47 16298103.16 4014384.71 3 212510 1208534.33 2981331.25 2945413.55 15768770.83 4051289.15 4 230102 1287644.67 3184961.43 3137565.31 16688780.92 4151095.28 5 230637.67 1288495.33 3200649.42 3152056.03 16724184.97 4187274.63 6 221493 1246650.33 3083842.4 3035333.78 16190034.53 3949535.79 7 222787.67 1255187.33 3089434.89 3057473.4 16272140.47 3992392.5 8 223005.67 1259632.67 3085842.16 3048434.67 16272318.29 3994932.62 9 212941 1199640.67 2971872.85 2942204.09 15793371.79 3845144.19 10 222130.67 1250665 3113776.5 3078244.39 16436491.02 4069680.8 average value 222710.135 1252933.566 3097248.578 3057995.89 16309981.54 4040422.587 SD 6329.855323 29951.82719 76902.35541 72666.94544 337917.9955 104305.2455 RSD% 2.84％ 2.39％ 2.48％ 2.38％ 2.07％ 2.58％

[0079] Kr gas injection meets the short-term stability requirement of RSD% ≤ 3%.

[0080] Long-term stability:

[0081] The time frame is 2 hours, 10 sets of data are collected, and the RSD% is calculated. In this example, only data is collected. 78 According to Kr's data, the acceptable standard is RSD% ≤ 3%.

[0082]

[0083]

[0084] The long-term stability of Kr gas injection meets the requirement of RSD% ≤ 3%.

[0085] Step 7, Precision determination:

[0086] Precision represents the degree of fluctuation in data within a single test group, reflecting the instantaneous stability and measurement accuracy of the entire system. Using Kr gas at a concentration of 1 ppm and a flow rate of 0.5 sccm, after the signal stabilizes, a new sequence is created with 10 main scans. The Kr elemental response value for each scan in this sequence group is recorded, and the RSD of the 10 data points is calculated. If the RSD value of each data group is less than 2%, the precision is considered acceptable.

[0087] Two sets of data were continuously collected using Kr gas injection, with each set of data collected ten times. The RSD of each set of data collected ten times was calculated, as shown in the table below. The acceptable standard is RSD% ≤ 2% for each set.

[0088]

[0089]

[0090] Kr gas injection precision is ≤2% RSD% per group.

[0091] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry, characterized in that, Includes the following steps: Step 1, Background noise measurement: An electron cyclotron resonance mass spectrometer (ECR-QMS) using an ECR ion source and a quadrupole mass analyzer was employed. Under normal instrument operation, an inert gas was introduced as the carrier gas. Under the set gas flow rate and vacuum conditions, a measurement sequence was established, a specific mass number was selected for signal acquisition, and the background noise value of the instrument was determined based on the average value of multiple scan counts. Step 2, Sensitivity Measurement: Under the same carrier gas conditions, krypton gas of the concentration to be measured is introduced, the mass spectrometer is tuned and the response value of a specific krypton isotope is measured. The average value of multiple sets of data is obtained and the background noise value is subtracted to obtain the sensitivity of krypton at that concentration. Step 3, determination of gas injection detection limit: The response values ​​of various krypton gas samples with different concentrations were measured, and the measurement standard deviation and detection limit were calculated. The formula for calculating standard deviation is: Where s is the standard deviation; x i This is a single measurement value; The average value is denoted by n; n represents the number of measurements. The formula for calculating the detection limit is: DL = 3s / S Where DL is the element detection limit; S is the sensitivity measured in step two; Step 4, Determination of oxide yield and double charge yield: Under the condition of mixed injection of krypton and oxygen, the count ratio of multiple isotope ions was determined to determine the oxide yield and double charge yield. The oxide yield and double charge yield were required to be less than 3%. Step 5, Isotope precision ratio determination: By scanning and measuring different krypton isotope ions, their isotope ratios and relative standard deviations (RSDs) are obtained. The RSD value of the isotope precision ratio is required to be less than 0.3%. The formula for calculating RSD is: RSD = (s / X) × 100% In the formula, s is the standard deviation; X is the arithmetic mean of the measured values; Step 6, Stability Test: Krypton gas was used for injection, and the gas flow rate was kept stable. A set of data was collected at intervals, and the data were recorded for 20 minutes and 2 hours respectively. The RSD of the data sets during this period was calculated to correspond to the short-term stability and long-term stability of this type of data, and both were required to be less than 3%. Step 7, Precision determination: Precision represents the degree of fluctuation in data within a group during a single test, reflecting the instantaneous stability and measurement accuracy of the entire system. Measurement precision is evaluated by calculating the RSD of the ion response value after multiple repeated measurements under fixed concentration conditions.

2. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step one, the inert gas used is argon, the gas flow rate is set to 0.5 sccm, and the vacuum degree is maintained at 1×10⁻⁶. -5 mbar to 6×10 -5 Between mbar.

3. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step one, the instrument parameters selected are: mass number 5, dwell time 20ms, number of channels 3, interval 0.01, and number of scans 20.

4. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step two, the instrument parameters are set as follows: gas flow rate is 0.5 sccm, and vacuum degree is approximately 5 × 10⁻⁶. -5 mbar, dwell time 20ms, number of channels 3, interval 0.

02.

5. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step three, the krypton gas concentrations are 0 ppm, 1 ppm and 10 ppm respectively, and 10 sets of data are scanned at each concentration, with each set being scanned three times.

6. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step four, the isotope ions measured include 80 Kr + , 84 Kr + as well as 42 Kr ++ , 96 KrO + and calculate 42 Kr ++ / 84 Kr + , 96 KrO + / 80 Kr + The magnitude of the double charge yield and oxide yield were obtained.

7. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step five, the selected isotope is 82 Kr and 83 Kr, instrument parameters selected: number of channels 3, dwell time 50ms, number of scans 100.

8. The method for determining krypton isotopes based on electron cyclotron resonance mass spectrometry according to claim 1, characterized in that: In step seven, a krypton gas with a concentration of 1 ppm is injected at a flow rate of 0.5 sccm, and the number of scans is 10. If the RSD of all 10 scans is less than 2%, the precision is considered to be qualified.

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