This work details technical advancements in multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for high-precision plutonium (Pu) isotope ratio analysis. Uranium (U) and Pu isotopes have been proven to exhibit similar mass fractionation effects, as measured using MC-ICP-MS, within analytical uncertainty. Herein, 233U-236U double spike method with IRMM3636 was developed to correct the mass fractionation while measuring Pu isotope measurement, achieving an RSD% of 0.0029 % for Pu isotope ratios at 10-2 level. This method was the first one to precisely measure low-abundance isotopes such as 241Pu and 242Pu via combining Faraday cup (1013 Omega amplifier) and secondary electron multiplier detector configuration. At trace levels (ng), long-term RSDs of 239Pu at a laboratory working standard reached 0.019 % (241Pu/239Pu) and 0.046 % (242Pu/239Pu) near the 10- 4 level, demonstrating exceptionally high precision in the isotope ratio analysis and representing the highest precision reported to date for these ratios. This state-of-the-art method maintained high sample throughput while delivering exceptional accuracy. Its robustness was confirmed through successful application to Pu isotope analysis in irradiated nuclear fuel samples, highlighting its broad applicability.

Thermal ionization mass spectrometry (TIMS) is a widely used mass spectrometric technique for trace/ultra-trace isotopic analysis. For accurate isotope ratio determination, the detector dead time and ion counter efficiency have to be appropriately corrected for. Two methods of pulse counting detector dead time calculation were evaluated on a TIMS instrument. Both methods were based on the measurement of Sr isotope ratios in NIST standards and had similar performance in assessing the dead time for pulse-count detectors. In addition, one of the newly proposed methods in this manuscript can be used to simultaneously determine the dead time and ion counter efficiency of the pulse counting detector via the ratio measurement approach. The advantages of using the method presented here are firstly that both the detector dead time and the ion counter efficiency can be obtained simultaneously and secondly that the sampling time can be spent entirely on the isotopes of interest.

Resonance ionization mass spectrometry (RIMS) is a highly sensitive technique for isobar-free analysis of long-lived isotopes, leveraging its exceptional elemental selectivity. However, the inherent laser-induced isotopic discrimination (LIID) in RIMS has posed challenges for its application in high-precision isotope ratio analysis. To address this limitation, based on the experimental phenomena observed in the analysis of Sn isotope ratios using RIMS, we investigated how isotope mass and isotope shift affect ionization efficiency, and proposed a semi-empirical internal standard correction method for LIID. Additionally, the combination of the total evaporation method, which is commonly used in thermal surface ionization mass spectrometry (TIMS), with RIMS effectively corrects the influence of mass fractionation on ratio measurements, thereby decoupling the LIID from the mass fractionation. This novel internal correction model for LIID enables RIMS, for the first time, to perform isotope ratio measurements with internal calibration capabilities comparable to those of TIMS and inductively coupled plasma mass spectrometry (ICP-MS). The application of this correction method to Sn isotopes has led to a tenfold improvement in both precision and accuracy. Post-correction analyses demonstrated isotope ratio determinations with precision better than 0.05% and accuracy exceeding 0.1%. This advancement significantly expands the potential of RIMS in fields that demand strict isotopic fidelity, such as nuclear forensics, the nuclear industry, and environmental tracer studies.

Many numerical simulation models for analytical and industrial ICP sources have been developed; hence, experimental verification is essential. Compared with plasma temperature, the flow velocity profile is a direct and reliable criterion for model verification. In this paper, an experimental study on the dynamic properties of a home-made analytical ICP source and its tail flame is conducted using a high-speed colour camera and a high-speed fibre-optic spectrometer, and the spatially resolved pulsation frequency and flow velocity are presented. The pulsation frequencies of the plasma area and emission intensity were experimentally determined, respectively. The spatially resolved pulsation frequency indicates that pulsation of the normal analytical zone (NAZ) is very stable and synchronous, and the tail flame fluctuates due to ambient air entrainment. The flow velocity in the coolant gas was characterised by tracking the trajectories of injected alumina powder particles. After correcting for the velocity difference between the powder particle with high inertia and the surrounding flow, a plausible range of axial (Vz) and radial (Vr) velocity at the outer edge of the coolant gas is proposed. The flow velocity on the axis downstream of the NAZ was experimentally determined by tracking and interpolating the velocity of discrete erbium ion clouds originating from individual erbia suspension particles. By comparing the simulated profile of axial velocity with the experimental profile, the power coupling efficiency of the present ICP facility is estimated to be around 80%. A linear expression is presented to describe the variation of Vz with the axial position (z) in the range of 0 <= z <= 50 mm. Because erbium ion clouds were not distinguishable from the very bright emission background within the NAZ, a novel method is proposed to determine the flow velocity in the NAZ by combining the dependence of the audio frequency of plasma pulsation on the flow velocity profile, the simulated profile of axial velocity, and the experimental value of pulsation frequency. The determined value of axial velocity at the torch outlet axis operating at an r.f. power of 1200 W is in good agreement with the fitted value. This work presents complete experimental data on flow velocity in a single ICP facility and experimentally verifies the previously developed 2D numerical model.

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.

Radionuclide verification is one of four international monitoring systems that were stipulated by the comprehensive nuclear test ban treaty.The radioactive noble gas xenon is a gaseous fission product of nuclear fuels.The radionuclides of Xe are characteristic nuclides of nuclear explosion.A nuclear event that violates the treaty may be found by monitoring the variation of radioxenon(mainly ~(133)Xe~(m),~(133)Xe,~(135)Xe and ~(131)Xe~(m)) in global atmosphere through a global network of eighty stations of the international monitoring system(IMS).Therefore,it is necessary to research the sampling technology for xenon isotopes.The possibilities for sampling technology(including condensation and concentration of xenon isotopes) is explored from pre-separating and pre-condensing(microxenon) sample with FNQ-01 gas condenser experimental platform.The collecting efficiencies of microxenon influenced by the different condensing conditions were studied on this experimental platform.The best condensing conditions optimized with the orthogonal design method are showed respectively as follows: xenon concentration in sample 1.046×10~(-3),condensing temperature-198 ℃,gas flow rate 0.3 L/min,gas inlet pressure 55 kPa and evaporating temperature-50 ℃.The average collecting efficiency under these optimized conditions is 73%.Furthermore,the influences of different admitting methods to xenon collecting efficiency and condensation were discussed.

An experimental sampler for rare gases (ESRG) which can collect radioxenon isotopes from atmosphere under normal temperature and low temperature is installed and studied. Its sampling efficiency is calibrated with ICP-MS (Inductively Coupled Plasma-Mass Spectrum) through analyzing the ~129Xe in the off-gas of ESRG. The main experimental results show that the sampling efficiency to xenon isotopes in ambient air is up to 40% when the adsorbent is effectually regenerated.

研究了在空气和含NO2气氛中不同温度下对GF/Cu皮芯复合导电纤维材料加速老化,力学性能、电学性能的影响,以及空气中高低温冲击导致其力学性能变化的规律.给出了导电纤维材料在不同环境中的氧化动力学曲线并分别计算了氧化激活能,推算出室温(25℃)条件下不同气氛中的储存氧化半衰期分别为:13.55年(空气气氛)、216.29天(氧化性气氛NO2:空气＝1:1)和374.75天(氧化性气氛NO2:空气＝1:2).

The static adsorption isotherms and adsorption rates of krypton and xenon at 201 K on viscose-based activated carbon fibres(VACF),pitch-based ACF(PACF),and granular activated carbon (GAC) are measured on a Micromeritics ASAP 2010M specific surface area and pore size distribution instrument by changing working gas of the instrument from N_2 to krypton or xenon. The results show that VACF has the same equilibrium adsorption capacity, but different adsorption rates for krypton and xenon.Because of the difference in their adsorption rates,sampling or concentration of krypton and xenon with VACF may lead to an alternation in their molar ratios.

通过正交设计优化了玻璃纤维化学镀镍的工艺条件,在此条件下研究了施镀时间与镀速之间的关系,同时对导电玻璃纤维的镀层成分进行了分析.研究表明,玻璃纤维化学镀镍后,大大提高了导电性能,可用于制备电磁屏敝材料.

通过正交实验优化了玻璃纤维化学镀铜的工艺条件,研究了提高镀液稳定的方法,同时对导电玻璃纤维的电阻率、镀层成分等参数进行了分析.研究表明,玻璃纤维化学镀铜后,可提高导电性能,并用作制备电磁屏蔽材料.

The adsorption behaviors of the different activated carbon fibersto ultra-trace xenon in air are studied using the method of 133Xe as tracer. The efficiency equation of adsorption columns are determined. The comparison of adsorptive capacity between activated carbon fibers and activated carbon indicates that activated carbon fibers are better than activated carbon under low temperature.

This article studied the characteristic detection of xenon by photoionization detector (PID) and the dynamic adsorption of xenon by activated carbon fiber (ACF), two factors that influenced the dynamic adsorption of xenon by ACF were discussed. The result showed that xenon could be characteristic detected by PID; ACF had fine dynamic adsorptive capacity of xenon and was a fine adsorbent that could be used to absorb xenon.