Americium isotopes are crucial in various nuclear-related fields such as nuclear fuel cycle, nuclear forensics and nuclear safeguards. This study introduces enhanced methodologies for precise determination of 242Am/241Am and 243Am/241Am in trace americium by employing Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) and Total Evaporation-Thermal Ionization Mass Spectrometry (TE-TIMS). We established a standard-sample bracketing (SSB) method with uranium-certified reference material (U CRM) to correct the mass fractionation and ion counter gain yield among different isotopes in MC-ICP-MS. The new methods were successfully applied to an aliquot of an 241Am progeny sample, an 241Am activity standard solution and an in-house Am isotopic working standard, achieving detection limits of 10- 7 for 242Am and 243Am. Analysis requires an aliquot containing about 1 ng of 241Am for MC-ICP-MS with a desolvation device for sample introduction and about 5 ng for TE-TIMS to determine 242Am/241Am ratios close to 10-5 and 243Am/241Am ratios close to 10-4, with observed relative standard deviations of 0.2 %. Comparative analysis of 242Am/241Am and 243Am/241Am using classical TE-TIMS and the newly developed MC-ICP-MS confirms their consistency within uncertainties, validating the precision of MC-ICP-MS in americium isotope ratio determination. These findings indicate that the 241Am activity standard sample was directly sourced from irradiated material rather than from a 241Pu solution, highlighting the methodology's applicability to nuclear forensics and nuclear fuel cycles.

Precise and accurate analysis of 235U/238U, 234U/238U, 230Th/234U and 230Th/232Th in 15 uranium ore concentrates (UOCs) was achieved using ICP-MS for nuclear forensic applications. A novel method was developed to dating UOCs.

Americium isotopes are crucial in various nuclear-related fields such as nuclear fuel cycles, nuclear forensics and nuclear safeguards. This study introduces enhanced methodologies for precise determination of 242Am/241Am and 243Am/241Am in trace americium by employing Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) and Total Evaporation-Thermal Ionization Mass Spectrometry (TE-TIMS). We established a standard-sample bracketing (SSB) method with uranium-certified reference material (U CRM) to correct the mass fractionation and ion counter gain yield among different isotopes in MC-ICP-MS. The new methods were successfully applied to an aliquot of an 241Am progeny sample, an 241Am activity standard solution and an in-house Am isotopic working standard, achieving detection limits of 10−7 for 242Am and 243Am. Analysis requires an aliquot containing about 1 ng of 241Am for MC-ICP-MS with a desolvation device for sample introduction and about 5 ng for TE-TIMS to determine 242Am/241Am ratios close to 10−5 and 243Am/241Am ratios close to 10−4, with observed relative standard deviations of 0.2 %. Comparative analysis of 242Am/241Am and 243Am/241Am using classical TE-TIMS and the newly developed MC-ICP-MS confirms their consistency within uncertainties, validating the precision of MC-ICP-MS in americium isotope ratio determination. These findings indicate that the 241Am activity standard sample was directly sourced from irradiated material rather than from a 241Pu solution, highlighting the methodology's applicability to nuclear forensics and nuclear fuel cycles.

The characteristics of enriched uranium materials are very important for nuclear fuel cycle and nuclear forensic analysis.Among all those fingerprints,the urani-um isotope ratios and the uranium age are considered to be of major parameters for trac-ing the sources and process conditions.To the best of our knowledge,there are only a few relevant articles focusing on the analysis of 233 U isotope abundance.In most of the published literatures subjected to uranium age dating,either 230Th-234 U chronometer or 231 Pa-235 U chronometer was employed to determine the age of enriched uranium materials with the isotope dilution mass spectrometry and anion exchange separation procedure,where the most time-consuming step was the sample preparation.Hence,this project aimed to develop a fast and flexible method for the determination of the uranium isotope ratios,230Th/234 U and 231 Pa/235 U atom ratios of the enriched uranium samples by the combination of multiple collector inductively coupled plasma mass spectrometry(MC-ICP-MS)and triple quadrupole inductively coupled plasma mass spectrometry(ICP-QQQ-MS).The results showed that the limits of detection(LODs)of 233 U by Neptune XT MC-ICP-MS and Agilent 8800 ICP-QQQ-MS were 3 × 10-9 and 6 × 10-10,respec-tively,and the relative standard deviations(RSDs)of 233 U/235 U isotope ratios at the level of 10-7 by MC-ICP-MS and ICP-QQQ-MS were 1.0％(2a)and 4.8％(2a),respectively.The standard sample bracketing(SSB)method of ICP-QQQ-MS based on the calibration of GBW04240 reference material was established to correct the mass fractionation of 230Th/234 U and 231 Pa/235 U atom ratios simultaneously.The ages of the uranium materials were diagnosed by the two parent-daughter relations of 234 U-230 Th and 235 U-231 Pa,indicating that the LODs of age dating were 0.2 a and 0.5 a,respectively.Meanwhile,the isotope ratios of 234 U/235 U,235 U/238 U and 236 U/235 U were determined by MC-ICP-MS.The fingerprints showed that the last purification time of the enriched uranium samples were around 2009 and the samples had been irradiated by the nuclear reactor.Overall,this method can reveal precise and accurate genetic signatures within one week,providing rapid technical supports for nuclear forensics,certification of nuclear reference materials and nuclear safeguards.

Xenon（Xe） isotopes from nuclear test and accidents are important monitoring components of the comprehensive nuclear test ban treaty（CTBT）.An approach for the reproducible and accurate compositional analysis of Xe isotope ratios by multiple collector inductively coupled plasma mass spectrometry（MC-ICP-MS） was described in this paper.A Xe enrichment and purification platform was established to separate Xe from the collected atmosphere gas,enriching the Xe concentration and utilizing high purity argon as aerosol carrier,thus resulting in eliminating the negative influences of organic compound and particles on mass spectrometry.A relible Xe injection system was built to control the gas flow rate between the sample and the MC-ICP-MS in order to improve the stability and reproducibility of the ion-signals.Furthermore,several measures,including adsorbing Xe from the sample gas for mass spectrometry and baking the Xe introduction device for 2 hours with vaccum pumping,were taken to reduce the Xe blank.As a result,the blank signal of 129 Xe falled from 3.0 × 10 -2 V to 2.7 × 10 -3 V.Analyses were performed on a Neptune XT MC-ICP-MS,and standard sample bracketing（SSB） was involved in correcting the mass fractionation.The approach was successfully validated by the measurement of standard reference materials in 24 hours,showing that the relative uncertainties for all Xe isotope ratios were less than 0.09%（n = 7）,while the results agreed with the certificated values within uncertainty range.Especially,the relative uncertainties for 130 Xe/ 131 Xe and 132 Xe/ 131 Xe ratios were 0.007 1% and 0.006 9%,respectively.Two kinds of atmosphere gas collected at different times were analyzed and distinguished successfully by the proposed approcach.The results demonstrated that the developed technique was a precise and accurate method for Xe isotope dectection,Xe monitoring event identification and event sourcing.

The commercial Hexin Single particle aerosol mass spectrometer (SPAMS) has been widely used for environmental aerosol monitoring and source apportionment. However, particle size measurement is easily affected by environment pressure fluctuation and sampling orifice clogging. The capability for quantitative analysis is poor, and few isotope measurement has been reported. This paper aims to evaluate the analytical performance of SPAMS and extend its application. First, the flight time of standard particles having different densities and sizes was measured under various conditions (aerodynamic lens upstream pressure and carrier gas). We proposed a universal method for particle size calibration, measurement and correction, taking into account the effects of lens geometry (acceleration nozzle diameter), particle parameters (density, diameter, and shape factor), and operating conditions (lens upstream pressure and carrier gas). Then, isotope measurement was performed when introducing a solution droplet containing a single element. Metal oxide and metal cluster ions were observed in the mass spectrum, indicating incomplete ionization of the sample droplet. The mass discrimination effect was carefully evaluated to correct the measured isotope ratio. Results show that the achievable accuracy of the corrected isotope ratio for elements investigated was 5%. The instrumental performance was relatively poor for elements having great ionization potential or bond energy. Finally, Ag/Eu2O3 suspension and yellow cake/ ethanol suspension were analyzed for size, elemental and isotopic analysis. We confirmed that the mass discrimination effect during suspension introduction could be corrected using the mass discrimination correction factor obtained during solution introduction. The Ag, Eu and U in these suspension particles were all found to be at natural abundance. The uranium in the yellow cake was identified as sodium duranyate (Na2U2O7) with volumetric equivalent diameter of approximately 65 nm. The work presented here is beneficial for instrument improvement and wide application.

Determination of thorium isotopic ratio Th-230/Th-232 in uranium materials by multiple collector inductively coupled plasma mass spectrometry ( MC-ICP-MS ) was presented for nuclear forensic. One piece of UO2 formed uranium pellet and three kinds of yellow cake powder were dissolved with ultrapure HNO3 (7. 5 mol/L) . Thorium was purified for analysis using a single column prepared with TBP resin bed , with which the sample was loaded and then Th was eluted with 4 mol/L HCl. Analyses were performed on Nu Plasma MC-ICP -MS and mass-bias correction were applied to the Th-230/Th-232 using bracketing measurements of U standard. An equation was proposed to correct the contribution from Th blank for calculating the Th-230/Th-232 of the uranium materials. The results showed that the Th-230/Th-232 ratios of the uranium pellet, yellow cake powder named YC1 , yellow cake powder named YC2 and yellow cake powder named YC3 were (0. 479 +/- 0. 037) , (1. 376 x 10(-4) +/- 4. 8 x 10(-6)) , (2. 8582 x 10(-3) +/- 2. 2 x 10(-6) ) and (2. 8605 x 10(-3) +/- 2. 1 x 10(-6)) (k = 2) , respectively. The determined Th-230/Th-232 ratio of the uranium pellet agreed with the reference value. The yellow cake powder named YC2 and the yellow cake powder named YC3 were from the same source, whose Th-230/Th-232 ratios agreed with each other and differed distinctly from that of another sourced yellow cake powder named YC1 . It was proved that the thorium isotope ratio Th-230/Th-232 was a newly discovered and time correlated fingerprint of uranium materials.