Uranium ore concentrate (UOC) is a group of intermediate products widely used in the nuclear fuel cycle. Following the recent characterisation and classification of UOC industrial product powders for nuclear forensic analysis, this paper presents an experimental study of the hygroscopic properties of these UOC stockpile samples for long-term storage and the inhalation risk assessment of uranium particles. Two independent techniques, the density balance and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), were utilised to measure increases in sample weight and the infrared absorption peak of ten UOC samples, respectively, due to hygroscopic growth. Taking (NH4)4((UO2)2(SO4)O2)2(H2O) powder as an example, the hygroscopicity mechanism was investigated experimentally by monitoring hydration and dehydration processes using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Thermogravimetric-Differential Thermal Analysis (TG-DTA), respectively. The hygroscopic growth factor of (NH4)4((UO2)2(SO4)O2)2(H2O) sample was determined using the above two techniques under precisely controlled temperature and humidity conditions. Screening results show significant differences in the hygroscopicity of sodium- and ammonium-containing UOC powders, despite their similar elemental composition, infrared functional groups, and crystal structures. The porous surface and hygroscopic component are beneficial for hygroscopic growth. Observation of the hydration and dehydration process confirms that the physical adsorption of water is the dominant mechanism. The hygroscopic growth factors of sample mass and infrared absorption peak increase with rising relative humidity above 80% RH. The hygroscopic growth curve of (NH4)4((UO2)2(SO4)O2)2(H2O) powder could be described using a simplified κ-Köhler equation. A dense surface, low RH (<80%) and an inert buffer gas are recommended for material processing and stable storage. For (NH4)4((UO2)2(SO4)O2)2(H2O) particles possibly inhaled in the respiratory tract, the effect of hygroscopic growth on the deposition profile is also discussed.

In this study, we extend our previous high-speed photographic studies (Xie et al. 2022 and Han et al. 2025) to direct characterization of the central channel and its flow velocity distribution in an analytical inductively coupled plasma source. The strong plasma emission was successfully suppressed by optimising the high-speed camera's aperture size and shutter duration, allowing us to directly observe the central channel and the discrete ion cloud. The width of the central channel was determined from the luminance distribution rather than the analyte ion distribution, unlike the commonly used method. The effect of the addition percentage of oxygen and nitrogen to the sample flow on the channel width was investigated. By injecting and tracking five types of suspension particles with various inertial properties, the axial flow velocity in the central channel was determined using the time-of-flight method. The axial flow velocity distributions at varying r.f. power, sample flow rate, and addition fraction of oxygen and nitrogen in the sample flow were finally experimentally determined. Results show that the width of the central channel in pure Ar-ICP is 7.2 mm under the investigated operating conditions. The presented width value is comparable with the peak-to-peak distance of the plasma parameter distributions but about three times that determined from the analyte ion distribution. In the mixed-gas ICP, the width increases with increasing nitrogen addition percentage in the sample flow but is insensitive to the oxygen addition fraction. Compared with the flow velocity, no particle slipping or dragging was observed, indicating that the flow velocity was well represented by that of the suspension particles used. In pure Ar-ICP, Ar-O2 ICP and Ar-N2 ICP, the axial flow velocity tends to increase and then decrease with the axial position with respect to the torch outlet. In pure Ar-ICP, a cubic polynomial fitting of the axial flow velocity with the quadratic root of the axial position is proposed for velocity estimation. A velocity plateau is clearly observed in the normal analytical zone (NAZ). The present work provides detailed information on the central channel for pure argon, Ar-O2 ICP, and Ar-N2 ICP. Experimental data on the axial flow velocity distribution across a wide range in the ICP source are also presented.

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.

A high accuracy method for Xenon isotope abundance measurements was developed on a Helix MC Plus static gas mass spectrometer，in order to solve the problem that the mass difference of the nine stable isotopes of Xe is large (about 9.6%) and the mass spectrometry detector is difficult to accept, for get the abundance of all the stable isotopes of Xe quickly and accurately. The gas sample containing Xenon was purified and separated before introduced into the mass spectrometer analyzing chamber firstly, which helps reducing the influence on Xenon isotopic measurement brought by other noble gases and active components. Then, a measurement method combining peak hopping and multi reception was used to achieve high precision measurement of all stable isotopes of Xe at extremely small sample amount based on the Helix MC Plus static gas mass spectrometer. The measured data were corrected by referring to the Xenon isotopic reference gas finally. Results show that, under the condition of small sample amount (approximately 1.12×10-12 mol), the relative standard deviation (RSD) of the measured 129Xe/132Xe, 130Xe/132Xe, 131Xe/132Xe, 134Xe/132Xe, 136Xe/132Xe were within 0.24% by Faraday, and 124Xe/132Xe, 126Xe/132Xe were within 0.22% and 0.39% by counting method separately. This method achieves abundance ratio analysis of trace Xe stable isotopes with good stability and high accuracy.

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.

Numerical simulation and theoretical prediction show that the observed exponential decrease of the a.f. noise frequency with sampling depth in an ICP source result from a coupling effect of vortex dissipation both at torch outlet and sampling gap.

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.

铀颗粒物中230Th与234U物质的量比值n(230Th)/n(234U)可用于诊断铀材料的生产年龄.转移并消解多个不同铀丰度的CRM124-4,GBW04234和GBW04238铀颗粒物制备最初溶液,分样后在各溶样瓶中分别加入定量的233U稀释剂和229Th稀释剂.其中,加入229 Th稀释剂的230Th定量样品进一步分离纯化去铀,采用多接收电感耦合等离子体质谱仪(multiple colletor inductively coupled plasma mass spectrometry,MC-ICP-MS)分别 测定n(238U)/n(233U)和n(230Th)/n(229Th),由同位素稀释质谱法得到最初溶液中238 U的质量分数w(238U)和230Th的质量分数w(230Th).待测铀颗粒物中n(238U)/n(234U)已知,计算出最初溶液中w(234U)及n(230Th)/n(234U),最后诊断出颗粒物的生产年龄.研究结果表明:6.1×10-5～3.8×10-4 g 量级 CRM124-4,GBW04234 和 GBW04238 铀颗粒物中n(230Th)/n(234 U)测量值的相对偏差分别为 2.7％、6.1％和 1.8％;CRM124-4,GBW04234 和GBW04238所对应铀材料的生产年龄诊断结果分别为57.81±1.55 a,23.32±1.42 a和22.99±0.40 a(2σ),诊断精度达到国际同等先进水平.

Diffusion coefficient of water in nitrogen (Dvg) is a critical thermophysical parameter. However, the widely used empirical parametrizations of Dvg are only applicable in the temperature range from 273 K to 373 K. In the supercooled range, the reported experimental values of Dvg is sparse, and Dvg varies with temperature in a way different from the empirical equations and the recently reported first-principles calculation. In this paper, Dvg values at given temperatures, including in the supercooled range, were determined using the evaporation kinetics of individual water droplets in nitrogen flow under well-controlled conditions. The KVH model capable of describing the rapid evaporation/condensation process of an individual water droplet was utilized, and the thermophysical/kinetic parameters were evaluated carefully. Through reviewing the literature values of mass accommodation coefficient (αM) for ice, ice with liquid-like layer, supercooled water, normal water, and hot water, it is observed that the Slogistic1 function presented by OriginPro® could describe the temperature dependence of αM well. Then, the radius vs. time curve of an individual water droplet was predicted from the KVH model by varying Dvg and then compared with the experimental curve recorded by the Electrodynamic Balance. The trial value of Dvg corresponding to the best agreement was treated as its experimental value. By reviewing and regression fitting of all available experimental data, an improved expression of Dvg is proposed. The accuracy is evaluated to be ± 4 % in the temperature range of 248 K to 600 K.

Ultrahigh-volume samplers with a flow rate of approximately 500 m(3)/h are widely used for atmospheric radionuclide monitoring. These samplers are often shut down during heavy particulate pollution due to filter clogging. We proposed a solution involving sampling with an impactor to reduce the filter clogging and avoid sample loss. A multislit impactor was designed to keep its low pressure drop and to save space in the context of an ultrahigh flow rate. Nonwoven cloth was chosen as impaction substrate for a low cut size, high dust capacity, and convenient operation. An undulating jet plate was designed to reduce particle loss on its surface and this was predicted by computational fluid dynamics (CFD). The test experiment results show that the cut size of the impactor is approximately 1.5 mu m, and the particle loss is only 5% with loess aerosol as the challenge. Field tests show that the atmospheric large particles collected by the impactor was average approximately 0.53; the concentrations of I-131 and aerosol mass are consistent with those from commercial Hi-Vol total suspended particles (TSP) sampler (63 m(3)/h) by +/- 10%. Results from the laboratory and field tests suggest that the impactor presented in this study constitutes a major improvement in the reduction of the filter clogging in ultrahigh-volume aerosol samplers under heavy particulate pollution. (C) 2019 American Society of Civil Engineers.

BioSampler is now being widely used for bioaerosol sampling. However, the sampling efficiency in wide size range especially for nanoparticles as well as the size-dependent retention efficiency have not been well evaluated until now. Through literature review, theoretic analysis and experiments, this paper reviews the sampling process, collection mechanism and sampling performance of commercial BioSampler including pressure drop as a function of sampling flow rate, the mass loss rate and temperature of the collection fluid as a function of sampling time, the variation of retention efficiency with time, and the sampling efficiency in wide size range from nanometers to microns. The effects of low pressure and high relative humidity on determination of sampling efficiency in literature were carefully analyzed. To compensate the collection fluid loss and extract the insoluble/dissolved sample for further analysis, Continuous-Extraction BioSampler (CEBS) is proposed. The retention efficiency for particles of different sizes as well as the collection efficiency were determined and found to be identical with commercial BioSampler when no steam was introduced into CEBS. Finally, the combination uses of CEBS and Inductively-Coupled-Plasma Mass Spectrometer (ICP-MS) was developed. Exponentially Modified Gaussian (EMG) Model was derived and verified to describe the temporal concentration of the dissolved component originating from individual soluble droplet. Using internal standard calibration method and EMG fitting of signal curve, the target element amount in individual droplet could be determined accurately. For continuously-collected soluble droplet with duration of minutes, the observed signal curve can be described by EMG model and the fitted value of area varies linearly with the sample amount introduced. This paper not only provides comprehensive performance evaluation of commercial BioSampler, but also demonstrates that the proposed CEBS-ICPMS is capable of monitoring environmental coarse aerosol with time resolution of similar to 17 min.

颗粒物分析在核、环境、生命科学等领域具有重要价值,不经复杂化学处理直接将颗粒物引入高灵敏电感耦合等离子体质谱(IC P-M S)分析,具有分析速度快、可获取单颗粒特征信息、化学处理工作量小等优势.本文综述了气载、液载颗粒物直接进样IC P-M S分析技术,介绍了该技术在高效过滤器下游复杂基体气溶胶样品中的超痕量钚检测和悬浮液中单个氧化铒颗粒的高精度同位素分析中的应用,并从技术发展和分析应用角度进行了展望.

Laser-resonance-ionization time-of-flight mass spectrometer (LRI-TOF-MS) has been widely used in the analysis of trace isotopes because of its advantages such as high isotope selectivity, high sensitivity, and capability to receive all isotopes in a single measurement. A LRI-TOF-MS was built in our laboratory to search for efficient laser resonance ionization scheme of some elements and analyse their isotopic composition. To improve the resolution and suppress the peak tail, the orthogonal-acceleration technology was used in LRI-TOF-MS for the first time, and the design method of electrical parameters of TOF mass analyser with dual-stage reflectrons was derived. The developed ion guide device consisted of several different electrostatic lenses and was manufactured through theoretical analysis, SIMION simulation and experimental evaluation. The results show that the LRI source and the TOF mass analyser matched well in performance. (C) 2018 Published by Elsevier B.V.

The two-color three-photon photoionization technique was used to obtain information on high-lying excited even-parity levels of atomic neodymium in the 32,100-35,300 cm(-1) energy region. 417 even-parity levels, most of which were reported for the first time, were revealed. Out of these, 172 levels were assigned unique J values based on the J-momentum selection rule. The absolute accuracy of these levels was estimated to be better than +/- 0.2 cm(-1). (C) 2018 Published by Elsevier B.V.

Numerous analytical models have been applied to describe the evaporation/condensation kinetics of volatile components from aerosol particles for use in many applications. However, the applicability of these models for treating cases that lead to substantial and rapid changes in particle temperature due to, for example, evaporative cooling remain to be compared with measurements. We consider three typical treatments, comparing predictions of the evaporation rates of pure water droplets over a wide range in gas phase relative humidity (RH) and exploring the sensitivity of the predictions to uncertainties in the thermophysical gas and condensed-phase parameters. We also compare predictions from the three treatments to measurements of the evaporation rates of pure water droplets with varying RH using an electrodynamic balance (EDB), concluding that only two of the model treatments are sufficiently able to account for the level of evaporative cooling (typically as high as 12 K). Finally, we show that the RH can be inferred accurately from the evaporation rate of pure water droplets over the full range in accessible RH and comparison with the model predictions (within absolute uncertainties of 2.5% RH over the range 20% to 95% RH), considering the level of agreement with independent measurements made through determining the equilibrated size of aqueous sodium chloride and sodium nitrate droplets.

The Microwave Plasma Torch (MPT) is an excellent excitation source for on-line monitoring of environmental samples.